A fitness electronics company is a first-mover in wearable fitness trackers. Its innovative everyday activity and exercise bracelet has created a monopoly for its product. Executives are apprehensive about the company's ability to maintain its competitive advantage because they know that rival companies have competent research and development skills and access to complementary assets. These rivals are considered:

a. barriers to imitation.

b. first-movers.

c. complementary assets.

d. capable competitors.