Which of the following are the functions of the Central Bank of India?
1. Regulation of currency and flow of credit system
2. Maintaining exchange value of rupee
3. Formulating monetary policy of India
4. Supervisory powers over the indigenous bankers and leasing companies
(a) 1 and 3
(b) 1, 2 and 3
(c) 1, 2 and 4
(d) 1, 2, 3 and 4