The correct answer is C.
When you are multiplying by a factor to get an answer, you need the units to cancel. Since we have seconds to start with, we need to divide by seconds to get them to cancel. That's why it's important for seconds to be on the bottom.
Also, knowing that there are 60 seconds in 1 minute makes B and C the only possible answers. Since C has seconds on the bottom, it is the right choice.
