What is a coup d’etat?

a) a rejection of the ideas of a government
b) a sudden overthrow of an existing government
c) a civil war between groups within a country
d) a war against a country that used to be an ally

The correct answer is B. A coup d'etat is a sudden overthrow of an existing government.

A coup d'etat consists in the overthrow in an illegal and often violent event (by one or more subjects, popular or national elites, either independently or with the direct or indirect support of an institutional body such as the armed forces), of the constituted power, in order to cause a change of regime.

B) a sudden overthrow of an existing government

Explanation:

a.   it resulted in widespread unemployment.