Which numbers are necessary to solve this problem?

Brian goes to the gym 3 times a week. He exercises for 45 minutes each visit. Fifteen of those minutes are spent on weights and the rest are spent on the treadmill.

How much time does Brian spend on the treadmill in 4 weeks?

A.
3 times a week, 45 minutes, 15 minutes, 4 weeks

B.
3 times a week, 15 minutes, 4 weeks

C.
3 times a week, 45 minutes, 4 weeks

D.
3 times a week, 15 minutes