(D) This refers to make-shift homes that are typically built by individuals in an unplanned fashion and are constructed by scavenged materials such as repurposed zinc sheets and recycled lumber. 

(Eg) For example, Dharavi slum in Mumbai, India, is the world's largest slum housing about a million residents. 

(D) Housing out of necessity and based on the availability of land. Residents illegally occupy the land and are at risk of eviction (being removed from the property) by the legal owners. 

(Eg) For example, slums in Chennai, India have been demolished by the government as the land does not belong to slum dwellers. 

(D) This refers to residents having lack of access to basic services such as electricity, water and sanitation. 

Thus, residents resort to illegally tapping into nearby electrical grids and collecting water from nearby pipes. The risk of injury, ill-health and waterborne diseases is very high.

(Eg) For example, Tondo slum in Manila, dwellers illegally tap electricity from the national grid.

(D) This refers to land needs to be cleared to make space for the building of houses and the urban population as cities grow.

(E) When the forest or natural environment is cleared, it reduces the earth’s ability to convert carbon dioxide into oxygen, more carbon dioxide increasing heat trapped in the atmosphere, leading to global temperatures rising.

(Eg) About 18.7 million acres of forests are lost each year, equivalent to 27 soccer fields every minute.

(D) This refers to an increased need for resources to meet the demands of the city 

(E) As populations within cities grow, more resources like food, water and building materials are needed, leading to over extraction of natural resources, damaging the natural environment.  

(Eg) Large cities use about 504 billion litres of water a day and 1 in 4 cities is water-stressed. 

(D) This refers to the introduction of substances that do not normally belong in the environment can harm plants, animals and humans. 

(E) When cities lack proper waste disposal and it is disposed of crudely, it leads to the spread of diseases, resulting in people falling ill and lowering the standard of living. 

(Eg) For example, the United States of America produces 258 million metric tonnes of waste in 2017, as compared to Japan which produced 44 million metric tonnes. 

(D) Housing provides people with basic needs such as running water, sanitation, and electricity. 

(E) When people have basic needs provided for them, this will improve their quality of life because it will reduce the outbreak of disease. 

(Eg) In Singapore, all housing provided by the Housing Development Board (HDB) is required to meet the basic needs for human habitation. 

(D) Housing close to amenities such as grocery shops and hawkers for food, and clinics for medical needs. 

(E) When housing is close to amenities, it is more convenient to access them, as travelling time is reduced and can be put to other uses. 

(Eg) In Singapore, Queenstown was the first satellite town designed to be self-sufficient with schools, shops and a market. 

(D) Housing provides opportunities for people to interact and bond. 

(E) When housing provides opportunity for social interaction, it will result in neighbours helping each other because people will develop a stronger sense of belonging and community spirit. 

(Eg) In Singapore, there are at least 108 Community Centres in neighbourhoods that organise programmes for residents to participate in. 

(D) This refers to providing a range of housing to cater for different groups. This includes ensuring that housing development can meet the needs of people of all ages and physical conditions. 

(E) When the needs of all groups of people are met, it creates an inclusive community, which creates a sense of belonging and increases commitment to the country. 

(Eg) For example, the inclusion of ramps in HDB flats and Braille systems in HDB lifts are some of the ways to make the neighbourhood for inclusive for the needs of people with special needs. 

(D) This refers to implementing environmentally friendly technologies into the construction of homes or the upkeep of homes. 

(E) When environmental features are incorporated, it helps to reduce energy and water consumption, leading to less stress on the water and energy supply. 

(Eg) For example, the installation of solar panels to offset electrical consumption, water-efficient fittings to minimize water consumption and the use of green roofs and walls to reduce surrounding temperatures are some ways HDB is trying to ensure long-term sustainability.