Why would a confederate system of government most likely unify under central authority ? i think the answer is b

a. to choose a state capital
b. to form an army for defense
c. to plan community space
d. to build bridges and roads,

b.) To form an army for defense A confederation is a union of sovereign states who generally want to govern themselves, but have come together for a common cause. It makes sense that they would unify to defend themselves against foreign threats.

The answer is d. spain.