What are the three types of indefinite-delivery contracts and what is the use for each type?

What are the three types of indefinite-delivery contracts and what is the use for each type?

• A. Definite Quantity - Provides for delivery of a definite quantity of supplies and services for a fixed period; Requirements - Provides for filling all requirements during a specified period (from one contractor); Indefinite Quantity - Provides for an indefinite quantity within stated limits.
• B. Definite Quantity - Open-ended; Requirements - Fixed number of orders; Indefinite Quantity - Not used.
• C. Definite Quantity - For services only; Requirements - For hardware; Indefinite Quantity - For software.
• D. Definite Quantity - None; Requirements - None; Indefinite Quantity - None.

Answer: (A)