In Texas, the most common security instrument for real estate loans is:

A mortgage is incorrect because while it's the standard security instrument in most states, Texas specifically uses deeds of trust instead. Mortgages involve only two parties (borrower and lender) and require judicial foreclosure in Texas.

A land contract is incorrect because it's a different financing arrangement where the seller retains legal title until the buyer pays in full, not a security instrument for traditional loans.

A promissory note is incorrect because it's the document that contains the promise to repay, not the security instrument that creates an interest in the property as collateral.