What would it take for humans to not only survive in the desert but to thrive in the desert and adapt to the environment?

I asume we'd need water, a place to either raise animals or enough animals to to hunt. We'd also need a place that would provide us with shelter. Also you can gather plants for consumption.

"d.) carbon dioxide and hydrogen sulfide"

the offspring would all be white. if the parents are both white flowers then they have the genotype rr, which when crossed results in an all white punnet square.