Here's a problem to solve: Two students each carry a box up to the third floor of a building. The total mass of each student and the box she is carrying is the same. Roberta makes the trip in 45 s while Mary takes 30 s. Which of the following statements best describes this task?

Among the 4 following options, which is the correct answer?

- A: Roberta does more total work than Mary.
 
- B: Mary does more total work than Roberta.
 
- C: Roberta has a greater power output than Mary.
 
- D: Mary has a greater power output than Roberta.
 