Which country would be most likely to join an intergovernmental
organization?

a. an aggressive country that believes countries should resolve
disputes on their own

b. a powerful democracy whose people worry about giving up any
political autonomy

c. a poor dictatorship that hopes to improve its reputation with other countries

d. a highly restrictive country that wants to avoid interacting with the
outside world

The country with "A powerful democracy whose people worry about giving up any  political autonomy" would be most likely to join an intergovernmental  organization.

Option B

Explanation:

Joining IGO is also beneficial in terms of increment of relationships with other states which may result in declination of economic walls, protection from attacking or opposition parties, may leads to several beneficial alliance in order to shield nation from future wars or crisis. Therefore, such actions highlight importance of Unity and development of nations.

A powerful democratic nation is most likely to join intergovernmental organization (IGO) because native people are worried about giving up any political right of self government, economic, security and prominence benefits too.