Final answer:
When a customer opens a bank savings account, the bank becomes a borrower, using the deposits to provide loans to others.
Step-by-step explanation:
When a customer opens a bank savings account, the bank essentially becomes a borrower. Banks act as financial intermediaries because they stand between savers and borrowers. Savers, or depositors, place deposits with banks, and in return, they receive interest payments for the use of their money. Meanwhile, borrowers receive loans from these banks and repay the loans with interest. The money that savers deposit into their savings accounts is often used by the banks to provide loans to borrowers. Therefore, the correct answer to the student's question is (c) borrower.