Subject: mathqa
Question: it takes 10 days for digging a trench of 100 m long , 50 m broad and 10 m deep . what length of trench , 25 m broad and 15 m deep can be dug in 30 days ?
Option: 
A: 400 m
B: 100 m
C: 89 m
D: 79 m
Answer: A