6. Which of the following is true?

I. A key objective under material requirements planning (MRP) is to use each work center’s capacity effectively II. A key objective under just-in-time (JIT) is to minimize flow times III. Just-in-time (JIT) systems are best suited to situations where demand is relatively constant

a. I only

b. I and II only

c. I and III only

d. I, II, and III