By criticizing the party that is in power, the party that is out of power serves a

function.

A incumbent

B watchdog

c bonding agent

D single-party

The party that is out of the power serves the function of a "Watchdog" by criticizing the party that is in power.

Explanation:

The role of a watchdog is that of a Protector or Guardian.

The political party that is out of the power always try to keep the general public aware by providing information about the policies of the government in power in order to prevent the abuse of political power in the hands of the ruling party