The correct answer is C. Discount Rate that equates PV of inflows and outflows relating to capital.
The cost of redeemable preference share capital is the discount rate that equates the present value of the future cash flows (dividends and principal repayment) to the initial investment.
The rate of dividend is the amount of dividend that is paid per share. The after tax rate of dividend is the rate of dividend after taxes have been paid.
None of the above options is the correct answer because they do not take into account the time value of money. The cost of redeemable preference share capital is a discount rate, which means that it takes into account the time value of money.