Today, we had an exam and one of the questions was:
...... he exercised more and more, he developed stronger muscles.
a) What b) Since c) Whether d) As
Since because I taught that the sentence could be "He developed stronger muscles because he exercised more and more". But after the exam, our teacher said that it's wrong and the correct option is
As because both of these sentences point to same time. I understand his explanation but why it can not be what I say? In my opinion both of these options (Since and As) are correct. Am I really wrong? if so, why?