The main role of banks in the nation’s economy is to
a store, lend, and invest money.
b store, lend, and borrow money.
c store, lend, and distribute money.
d store, lend, and approve money.

The first alternative is correct (A).

Banks play a key role in stimulating the country's economy in all productive and financial sectors. The operating mechanism takes place as follows: these institutions serve as safe places to store the finances of individuals and companies. So, stored is used to lend to other people and companies that need to make investments. In return, lenders receive interest, that is, while lending to banks, they are making an investment.

In short, banks are mediating between savers and borrowers. Savers invest by putting their money in the banks, and borrowers borrow in the form of credit.