Aubrey has been accepted into medical school, a most expensive undertaking. aubrey has student loans and grants that pay part of the expense, but not all; she still needs $5,000. aubrey asks her family friend, clara, if aubrey can borrow $5,000 and offers to pledge her mother’s diamond necklace to ensure she repays the loan. clara agrees and gives aubrey $5,000. aubrey insists that clara take the diamond necklace and keep it until aubrey repays all of the $5,000. to make sure that clara’s security interest is perfected, clara needs to _______