Aman, Ram, and Kapil can complete a work in 68 days, 51 days, and 17 days respectively. If they work on alternate days such that Aman works on first day, Ram works on second day, Kapil works on third day and then again Aman works on fourth day and so on, then find the approximate number of days in which 50% of the work is completed.

A

19 days

B

16 days

C

15 days

D

18 days