Answer: The correct answer is option a.
Explanation:
Prezygotic isolation is a mechanism by which mating and fertilization is prevented. Thus, it prevents the formation of a zygote.
It can be achieved by various reasons such as temporal differences (difference in mating seasons), habitat isolation, behavioural differences (different mating rituals such as different dance patterns, voice calls, et cetera), mechanical isolation, et cetera.
Thus, different breeding calls prevent the species to interbreed with each which ultimately prevent the formation of zygote formation.
Hence, it is a type of prezygotic isolation.
Okay so northern Africa and the Sahara desert is the best example of desertification.
2 ways humans have contributed to that is: 1) pastoral nomadism 2) little to no settlements to increase water supply
how it impacted the environment: so now the environment there is sandy, only organisms adapted for those extreme environment can live there ex. camel, cactus, etc.,
how it impacted quality of life: quality of life diminished, not enough water to sufficiently feed the populations, people live in extreme poverty, people are moving away, and the climate is very dry and hot, pretty much not a place anyone would want to live
http://eden-foundation.org/project/desertif.html
https://www.sciencedaily.com/releases/2017/03/170314111320.htm