In the context of the Management by Objectives method, which of the following instances represents the strongest objective that can be used?

a. Fiona sets the objective of increasing productivity by 20 percent in one month's time.
b. Gunther sets maximum daily output as the objective.
c. Aisha sets 50 percent reduction in wastage and 10 percent reduction in costs as the objective.
d. Claude sets better customer service and the drive to succeed as the objective.