Plural or singular

Hi all,

Please help me with this.
Which one is the correct instruction sentence?

"choose a, b, c, or d for the correct answer"

or

"choose a, b, c, or d for the correct answers"

I found these two sentences when I was doing an exam.

Basically there are 4 options provided in every question and we just need to choose one correct answer.

There are about 25 questions in this section.

Thank you.