Final answer:
The type of credit that does not require collateral or a co-signer is Unsecured credit. It is based on the borrower's creditworthiness and is exemplified by most credit cards and personal loans.
Step-by-step explanation:
Among the options a) Unsecured credit, b) Secured credit, c) Installment credit, and d) Revolving credit, the type of credit that does not require the pledging of an individual's collateral or a co-signer is a) Unsecured credit.
Unsecured credit is a loan or line of credit offered to an individual without the need for security in the form of collateral or a co-signer. It is typically based on the borrower's creditworthiness and promise to repay. Examples include credit cards and personal loans. In contrast, secured credit requires collateral, and installment and revolving credits may be either secured or unsecured, depending on the lender's requirements.