Among 4 people A, B, C and D, A takes thrice as much as B to complete a piece of work. B takes thrice as much time as C and C takes thrice as much time asD to complete the same work. One group of three of the 4 men can complete the work in 13 days while another group of three can do so in 31 days. Which is the group that takes 13 days?
- A, B, D