C. 8.1% Explanation: National Savings Certificates, popularly known as NSC, is an Indian Government Savings Bond, primarily used for small savings and income tax saving investments in India. These can be purchased from any Post Office in India by an adult (either in his/her own name or on behalf of a minor), a minor, a trust, and two adults jointly. These are issued for five and ten year maturity and can be pledged to banks as collateral for availing loans. Currently the 5-year National saving certificate has the interest rate of 8.1%.