Final answer:
To maintain the account, the agency can keep $900,000 in the trust account.
Step-by-step explanation:
In order to determine how much money belonging to the agency may remain in the trust account to maintain the account, we need to know the reserve requirement set by the Federal Reserve. The reserve requirement is a certain percentage of depositors' money that banks are required to keep on reserve. Let's say the reserve requirement is 10%. If the agency has $1 million in the trust account, the bank will need to keep $100,000 ($1 million x 10%) on reserve and can lend out the remaining $900,000. The agency can keep $900,000 in the trust account to maintain the account.