The correct options are statements 1 and 2. Firstly, retail investors can indeed invest in Treasury Bills and Government of India Debt Bonds through their Demat accounts in the primary market, facilitating easier access to government securities. Secondly, the Negotiated Dealing System-Order Matching (NDS-OM) is operated by the Reserve Bank of India to enhance transparency and efficiency in the trading of government securities. However, statement 3 is incorrect as Central Depository Services Ltd (CDSL) was not jointly promoted by the Reserve Bank of India and the Bombay Stock Exchange; it was set up by the Bombay Stock Exchange along with various banks and financial institutions. Understanding these systems highlights the Indian government's efforts to promote financial inclusion and streamline the trading of public debt instruments.