What are military commissions? (a)special courts that investigate wrongdoing by military officers (b)special courts set up by the executive branch to try suspected terrorists (c)special courts that try cases involving military offenses against civilians (d)a board of officers who make decisions on veterans’ appeals

Military commissions are special courts set up by the executive branch to try suspected terrorists. The correct option is B.
Military commission was created by an executed order which was signed by president Bush of the United States of America in the year 2001. The military commissions are given the responsibility to conduct trials of non natives which are accused of terrorism in the United States of America.