(d) To mitigate the risk of loan default.
If the borrower fails to repay, the lender can sell the collateral to recover the loan amount.
Source: Terms of Credit, Chapter 3
The passage clearly states: "If the borrower fails to repay the loan, the lender has the right to sell the asset or collateral to obtain payment." This directly points to risk mitigation / protection against default as the purpose of collateral. Options (a), (b), and (c) are not supported by the text and are incorrect.