Why did Sullivan Ballou serve in the army

he volunteered

Explanation:

July 29, 1861: After the bombardment of Fort Sumter in April 1861, President Lincon called on the states to provide 75,000 militia troops to put down the rebellion. Sullivan Ballou volunteered, and encouraged others to do so as well. He was commissioned a major in the second Rhode Island Infantry Regiment.

answer; i believe the correct answer is (4) flip a coin as each participant arrives,heads indicates assignment to the first group: tails indicates assignment to the second group;

answer; self-serving bias;