Subject: mathqa
Question: pipe p can drain the liquid from a tank in 2 / 4 the time that it takes pipe q to drain it and in 2 / 3 the time that it takes pipe r to do it . if all 3 pipes operating simultaneously but independently are used to drain liquid from the tank , then pipe q drains what portion of the liquid from the tank ?
Option: 
A: 3 / 8
B: 17 / 29
C: 3 / 13
D: 3 / 4
Answer: C