Question

contraption means :
a transverse and enclosed drain under a road or railway
a device or control that is very useful for a particular job
a beam used as a main support in a structure
a regulator for controlling the flow of a liquid

Explanation:

The word "contraption" refers to a device or a piece of machinery that is often cleverly - designed and useful for a particular task.

Answer:

B. a device or control that is very useful for a particular job