Body Sync Inc. is a chain of gyms. It offers a fitness package that allows its members to use the gym facilities for 12 months by paying only for 10 months. Included in the package are two health checkups and a gym kit. These add-ons by themselves are not very valuable, but as a package they can enhance the perceived value of the service offerings. In this case, Body Sync's primary value driver is
A. economies of scale.
B. learning-curve effects.
C. availability of complements.
D. experience-curve effects.
Answer: availability of complements