It is a coalition of states that coordinate their actions to deter or defend against military attack. What are we referring to?

Alliance Building

The correct answer is Option 2 - Alliance Building

Four components of traditional security policy are:

Deterrence.
Defense.
Balance of power.
Alliance building.

A fourth and related component of traditional security policy is alliance building. An alliance is a coalition of states that coordinate their actions to deter or defend against military attack. Most alliances are formalised in written treaties and are based on a fairly clear identification of who constitutes the threat. Countries form alliances to increase their effective power relative to another country or alliance. Alliances are based on national interests and can change when national interests change. For example, the US backed the Islamic militants in Afghanistan against the Soviet Union in the 1980s, but later attacked them when Al Qaeda—a group of Islamic militants led by Osama bin Laden—launched terrorist strikes against America on 11 September 2001.