Drop manholes at the junctions of sewer lines, are provided if_________.

A)
two sewer lines intersect
B)
sewer line runs along a main road
C)
ordinary manhole cannot be built
D)
invert level of a branch sewer is more than 60 cm that of the main sewer

Correct Answer :   invert level of a branch sewer is more than 60 cm that of the main sewer