How does MRP handle safety stock?

a$.$Uses safety stock to cover requirements when necessary

b$.$lgnores safety stock in its calculations

c$.$Generates planned order to maintain safety stock levels

d$.$Provides safety stock for all items at all levels

Which of the following may prevent effective shop floor control?

a$.$Lack of valid due dates

b$.$Lack of good management and measurement by shop managers

c$.$Lack of valid data

d$.$All of the above