Which of the following statements is true? a. the bonus army, frustrated by the senate's refusal to act, opened fire on the soldiers sent to guard them. b. herbert hoover tried in vain to convince the senate and the army to meet the veterans' demands. c. military troops, led by george patton and commanded by general douglas macarthur, fired tear gas into the veterans' camp. d. civilian observers, themselves victims of the depression, sympathized with the government's handling of the veterans.