Final answer:
Businesses primarily keep their cash in bank accounts for security and the protection offered by FDIC insurance. Interest and investments are secondary benefits.
Step-by-step explanation:
The primary reason businesses keep their cash in a bank account is to keep the cash safe. Banks provide a secure environment for funds, reducing the risk associated with holding large amounts of cash on hand. Additionally, the presence of Federal Deposit Insurance Corporation (FDIC) insurance gives businesses the confidence that their deposits are protected up to a certain limit, ensuring safety in case of a bank's failure.
While banks do offer opportunities to earn interest and for investments, and although the money may be needed soon for transactions, the foundational reason for utilizing bank accounts is the enhanced security they offer compared to other means of storing cash.
Therefore, the correct option to the student's question would be: a. to keep the cash safe.