Identify the type of body movement
placing an index finger on lips to request silence
regulator
illustrator
emblem
adaptor
affect display

The type of body movement in placing an index finger on lips to request silence is that of an emblem.

Explanation:

The action of trying to convey to stop another action in progress can be referred to as an 'emblem'. When an action is controlled by posing a counter-action that has a conventionally accepted meaning, the action that is performed to 'control' can be called as the 'emblem' action owing to the meaning pre-assigned to it.

Idont know which one is right   but i know that c is wrong and a might be wrong