In order to purchase an interest in a piece of land called Blackacre, Rihannon borrowed $100000 from Nick. As security for the repayment of that loan, she entered into a mortgage over a piece of property. Which of the following statement is true?

A) The transaction must have occurred in a registry system.

B) It is possible that Rihannon gave a mortgage over a diamond ring that she owned.

C) Rihannon must purchase free simple in Blackacre.

D) Rihannon must purchase Blackacre from Nick.