Clean Rinse Shampoo has been the leader of hair$-$cleaning products for about $40$ years. However, this company relied too long on its competency without refining or upgrading its product. As a result, other shampoo companies that began to offer organic shampoo gained a competitive advantage over Clean Rinse. This case is an example of

a$.$

resource flow.

b$.$

value chain.

c$.$

dynamic capabilities.

d$.$

core rigidity.