When scientists first started mapping human genes, they estimated that there were about 2 million genes. by the late 1990s, it was thought that there were only 100,000 genes, and then that number shrank to 19,000 in 2001. most scientists now believe that humans have about 21,000 genes. which statement describes these estimates?

I have the options on e2020. So first, we can definitely mark out D because no way did they stay the same over time. We can cross out B because as scientist "upgrade" over the years, their work will become MORE accurate. Not LESS accurate. So then we are left with A and C. We can cross out C because its doesn't really become accurate and less accurate over time. Then we are left with A which is our answer because scientist can only become more accurate as time goes by with all the new technology advancements they're making.

Hope this helped!! :D (please read whole thing so you understand)

b

explanation: