I had to put up my house as … for the bank loan.

1. Analyze the question The sentence is "I had to put up my house as _ for the bank loan." We need the word for something valuable offered to a lender to secure a loan.

2. Explain the concept Look at each word:

• Pledge: a solemn promise, or an item handed over as security. It can also mean the act of pledging. We would normally say "I pledged my house," not "put up my house as a pledge" in this common phrasing.
• Agreement: a contract or understanding. A house cannot be put up as an agreement.
• Collateral: an asset (like a house, land, or car) that a borrower offers to a lender to secure a loan. If the borrower fails to repay, the bank can take the asset.
• Surety: a person who takes responsibility for another's debt (a guarantor), or the guarantee itself. A house is not a surety, but a person can stand as one.

3. Solution "Put up ... as ___ for a loan" matches the standard banking collocation "put up as collateral." The house is the asset securing the loan, and that is the meaning of collateral.

4. Answer The correct option is C. collateral.

5. Tip Remember: collateral = property, surety = person. If a question asks about an asset the bank can seize, choose collateral. If it asks about someone who guarantees your loan, choose surety.