Which of the Following Conditions Must Be Satisfied Before a Mortgagee

Which of the following conditions must be satisfied before a mortgagee can forcibly sell up a property?

A) The mortgagee gave at least one month's notice in writing of its intention to sell.
B) The sale must be genuine,which is usually achieved by selling at a public auction.
C) The mortgagor is in default usually by failing to make at least one repayment.
D) All of the above