Service level is:

a. the probability of stocking out.
b. the probability of not stocking out.
c. something that should be minimized in retail.
d. calculated as the cost of a shortage divided by (the cost of shortage the cost of overage) for single-period models.
e. the probability of not stocking out and calculated as the cost of a shortage divided by (the cost of shortage the cost of overage) for single-period models