Correct option is D
Given:
P, Q and R can do a work in 15, 20 and 30 days respectively
Concept Used:
Ratio of time is inverse proportion to the efficiency
Solution:
Ratio of time of P, Q and R = 15:20:30 = 3:4:6
Efficiency of P, Q and R = 1/3, 1/4, 1/6=4:3:2
Therefore, P and Q are more than that of R.
Thus, correct option is PQ.