Step 1: Understand the question.
We must find the main source from which a bank gives loans.
Step 2: What a bank does.
A bank acts like a middleman for money. It takes money from people who want to save and lends it to people who need money.
Step 3: Where the money comes from.
People put money in banks through savings accounts, current accounts, fixed deposits, and recurring deposits. All this collected money is called deposits.
Step 4: How loans are funded.
The bank keeps a small part aside and lends the rest of these deposits to farmers, businesses, and individuals. So deposits are the real pool used for loans.
Step 5: Why the other options fail.
Interest and service charges are earnings, not the main lending pool. Self help group accounts are too small to be the chief source.
Step 6: Final answer.
Banks give loans mainly from deposits collected from customers.
\[ \boxed{\text{Deposits collected from customers.}} \]