Paired Comparisons test question?

CFA Level I Quant
#1

If told to test the Null hypothesis ‘the mean difference between samples A & B is same’, do we use (Paraphrased)

A) paired comparisons test on the difference between the two returns

B) T-test on differences between sample means

C) F-test (I know this is wrong)

I really cant figure out when to use paired comparisons and when to use t-test. Any guidance would be appreciated

#2

We use t-test with paired comparisions when population is normal and relationship between samples is dependent.