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)