​Rivalry among firms would tend to be highest if

A) ​the industry is growing quickly
B) the industry is growing slowly
C) the industry is shrinking
D) ​None of the above

When the industry is shrinking, there are fewer opportunities for firms to capture market share, leading to heightened competition and rivalry among existing firms as they try to maintain their market position. In a growing industry, there may be more opportunities for firms to succeed and carve out a niche, leading to lower rivalry. The speed of industry growth itself is not necessarily directly correlated with rivalry among firms.