Answer: a
reason:
if you take any of the numbers and plug it in it works
OM and OP will coincide a second time after 120 seconds. You could visualize it as ray OP moving at 3 degrees/second relative to OM.
Using this visualization, we find that OM makes 30*60*3/360 rotations (minutes * 60 * rotational speed/360 degrees in a rotation), which is 15, and that OP makes 30*60*6/360 or 30 rotations, which is 15 more than OM.
By definition, the prism volume is given by:

Where,
Ab: base area
L: long
Substituting values we have:
Answer: The volume of the triangular prism is: