Anjani can do a certain piece of work in 18 days. Anjani and Khushbu can together do the same work in 14 days, and Anjani, Khushbu and Sushmita can do the same work together in 9 days. In how many days can Anjani and Sushmita do the same work?
A29/4
B20/3
C21/2
D18/2