For this question you must use POE (Process of elimination)

If we talk about ability then it is singular, so must be 'has become more accurate'. E looks right for most part except in the end where it uses 'have'.

C although looks a bit awkward has no grammatical mistakes and more importantly retains the meaning too.

Can you please post these questions in Sentence Correction section henceforth.

I guess I’m confused as to whether the ‘ability of scientists’ is plural or singular.

Oops, sorry about that posting in wrong forum. I had initially planned on posting a CR question, but I changed my mind, and forgot to switch to the SC forum

thanks