A Government Security (G-Sec) is a tradeable instrument issued by the Central Government or the State Governments. It acknowledges the Government’s debt obligation. Such securities are short term (usually called treasury bills, with original maturities of less than one year) or long term (usually called Government bonds or dated securities with original maturity of one year or more). Major players in the G-Secs and Corporate Bond market include commercial banks and PDs besides institutional investors like insurance companies. PDs play an important role as market makers in G-Secs market. A market maker provides firm two way quotes in the market i.e. both buy and sell executable quotes for the concerned securities. Other participants include co- operative banks, regional rural banks, mutual funds, provident and pension funds. Through the Retail Direct scheme, individual investors can invest in Government bonds. In this scheme, individuals must register with the RBI for a Gilt Securities Account, called RDG or Retail Direct Gilt. RDG account holders can partake in the primary issuance of SG/CG/SGB/T-bill. One can directly invest In Corporate Bonds through apps like Zerodha etc. Hence option (d) is the correct answer.