Question

Consider the following pairs of parts:

1. Pair of gear in mesh           

2. Belt and pulley

3. Cylinder and piston

4. Cam and follower

Among these, the higher pairs are:

(a) 1 and 4                                 (b) 2 and 4          

(c) 1,2 and 3                               (d) 1,2 and 4