Profitable investment of a Commercial bank includes

Money at call and short notice
Discounting of bills
Treasury bills
All of the above

The correct answer is D. All of the above.

Money at call and short notice are deposits that can be withdrawn on demand or at short notice. They are typically invested in short-term assets such as treasury bills and commercial bills.

Discounting of bills is a process whereby a bank lends money to a customer on the security of a bill of exchange. The bill of exchange is a

document that is drawn by a seller on a buyer and is payable at a future date. The bank discounts the bill, which means that it pays the customer the face value of the bill less a discount. The discount is calculated as a percentage of the face value of the bill and is based on the time until the bill matures.

Treasury bills are short-term debt securities issued by the government. They are considered to be very safe investments and are often used by banks as a source of funds.

All of these investments are profitable for commercial banks because they offer a return on investment that is higher than the cost of funds.