Two persons 'A' and 'B' together can finish a piece of work in 16 days while 'B' and 'C' together can complete the same work in 20 days. If 'A' , 'B' , 'C' work together, the same work is completed in 12 days, then the number of days required for 'A' alone to complete the work is

A

30

B

25

C

28

D

24