M1 in India's money stock refers to currency (notes and coins in circulation) plus demand deposits (current account balances) plus other deposits with the RBI. This is the narrow measure of money supply. Option A (post office savings) is incorrect as these are not part of M1. Option B (total post office deposits) is incorrect as they're not included in M1. Option D (time deposits) is part of broader money measures like M3 but not M1.