Identify devices that can be used for modulation:

(a) ‘i’ and ‘iii’

(b) only ‘iii’

(c) ‘ii’ and some regions of ‘iv’

(d) All the devices can be used.

Answer:

The correct option is (c) ‘ii’ and some regions of ‘iv’

Explanation:

For modulation, devices that follow the square law are utilised. The characteristics indicated in graphs I and (ii) correspond to linear devices as straight line graphs.
The square law device is depicted in Graph II. The square law is also visible in several portions of graph IV.
As a result, the answer is confirmed (c).