Subject: mathqa
Question: abel can complete a work in 8 days , ben in 12 days and carla in 15 days . all of them began the work together , but abel had to leave after 2 days and ben 3 days before the completion of the work . how long did the work last ?
Option: 
A: 9
B: 10
C: 4
D: 8
Answer: C