wrong answer to exercise?

[Medio]

Hello everyone

I'm preparing for an exam that also includes an English test, and one of the preparation exercises asks to complete the following sentence:

"Working conditions __________ since the new manager __________ ."

The four possible options are as follow:

A) Have been improving / took over. (Risposta Fornita - Errata)
B) Will have improved / has taken in.
C) Improved / came over.(Corretta)
D) Bettered / walks in.

I chose (A), but it seems that according to the person who prepared this exercise the correct answer is (C). I Frankly disagree with this, so I would like to get a second opinion from teachers and native speakers.

Thank you for your help

[Alan]

I agree with you: A is the correct answer!