I am certain that you are likely well aware of what CRISPR is by now, but if you aren't, it is essentially singling out a specific gene that may need to be edited or appended. Once that gene is found, the DNA is unraveled and broken to then replace base pairs or insert a new string of DNA, thus creating a desired outcome. For this form of theoretical artificial human intelligence, genetic editing and engineering will be utilized in order to increase all aspects of the brain equating to increased intellectual output. If you were an astute viewer who read about some of the key genes necessary for human brain development, you would probably think that we could enhance or amplify the effects of those genes in order to achieve higher gyrification of the surface, higher total neocortex neuron count, and other important factors. Now clever you might think, "won't the brain get squished inside the skull then?" The answer is yes, so the endocranial capacity would need to expand in order to fit the brain's expansions. Now another issue comes up. Wouldn't it be pretty much impossible to be birthed if the skull is too large? Once again, yes. To solve that, the embryo would be placed with an artificial womb to incubate in a simulated environment without the limitation of a skull size being present. Other issues may arise simply due to the relation of the brain to the rest of the body such as energy intake, support of the larger head, and other possible head functions needing a redesign to suit the new skull. This remains ultimately the most "human" option of the other choices as it is all purely biological.

Intelligence in a dish sounds dystopian, but it's already at our doorstep. If that is too eerie to imagine, compare it to your computer. There are many past and ongoing studies regarding cultivating a brain. So far, they have been for comparison against computers such of that belonging to data centers as human brains are incredibly efficient in the energy department and other niche computational categories. What makes a brain so applicable to this topic is its potential for massive sizes due to no bodily limitations. If purely provided support from machinery to maintain life, it could theoretically function. Now the question is, are we actually able to support an organoid solely from the machinery provided to support its biological needs, is up for debate. Hypothetically if that objective was acquired, that brain organoid could very well be provided mechanical means of interacting with the world. Imagine bearing witness to a robot walking around, yet it has the exact same intellectual functions as you.