There is a question in the Kanzen Master N2 Textbook:
According to the answer sheet, the answer is c.
But I don't understand why a. and b. are wrong.
From what I understand of 上で in this context
A上でB まずAします。それからB・準備としてまず～してから、その後で次に続く行動をする Where it is necessary to do A first before doing B, A has significance for what happens to B
When asking someone else, a sentence was given to me that is natural
If this sentence is correct, why is a. wrong, what is the difference?