Please provide a step-by-step answer to the following question. thanks.

- Mr. and Mrs. Wilson approach their building society for a mortgage of 100,000 to put towards the purchase of their new home. - The building society offers them two choices: 1. A repayment mortgage with an interest rate of 12% p.a. compounded annually 2. An endowment mortgage with an interest rate of 12% p.a. compounded annually on the loan and an endowment scheme with a guaranteed maturity value of at least 100,000 with a growth rate of 10% p.a. 0 In both cases, annual compounding is undertaken by the building society over 20 years. Which option has the lowest cost to Mr. and Mrs. Smith