A can do a piece of work in 16 days. B in 10 days. A and B work it together for 6 days, and then A and B work it together for 6 days, and then C finishes it in 3 days. The time in which C alone can do the whole work

A can do a piece of work in 16 days. B in 10 days. A and B work it together for 6 days, and then A and B work it together for 6 days, and then C finishes it in 3 days. The time in which C alone can do the whole work is 
(a) 90 days 
(b) 100 days 
(c) 98 days 
(d) 120 days