Who can you choose? Artwork shown in museums or galleries or they have had articles written about them by reputable sources (example: Street Artists). See your teacher if you are unsure if your selection is suitable. You can choose artists from social media, like Instagram. There are tons to choose from however, only choose one from that source. Otherwise, it might be challenging to build up the cultural significance.
The work selected for comparison should come from contrasting contexts (local, national, international and/or intercultural). Ideally students should see one of the works firsthand.