The cheapest source of finance is
(a) debenture
(b) equity share capital
(c) preference share
(d) retained earning
The cheapest source of finance is retained earnings. Retained income refers to that portion of net income or profits of an organisation that it retains after paying off dividends. An organisation can reinvest its retained earnings or profits for the purpose expansion, modernisation, etc. It neither involves any fund raising cost nor any risk. Also, unlike other sources of finance it does not involve any obligation in terms of repayment.