When confronted with the bonus marchers, president hoover opted to:
a hank them for their service to the nation, and ask for their support in the tough times that lay ahead.
b. pressure congress to pay off the bonuses immediately
c. send army troops to disperse the marchers.
d. call for a congressional investigation of the bonus march

C. Send army troops to disperse the marchers.

Explanation:

The Bonus March also called Bonus Army was a march composed by WWI veterans with their families that went to Washington DC in 1932 to demand bonus payment due to wartime services.

During that period the US was in an economic hardship of the Great Depression and even though the Congress voted bonuses but they were not scheduled for payment. 

When the march reached DC President Hoover sent army troops to disperse the marchers. The troops led by General Perry L. Miles destroyed their encampments and used tear gas and tanks.

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