$3.$ In the toothpaste industry, three brands make up a majority of the U$.$S$.$ market: Crest, Sensodyne, and Colgate. These brands all offer tooth$-$whitening options, contain fluoride, and are marketed as promoting oral health and fresh breath. Which is NOT an answer as to why rivalry among existing competitors is high for the toothpaste industry?

$*$

Competitors are roughly equal in size and power.

The growth rate of the industry is high.

Switching cost from one brand to another is high.

Excess capacity exists in the industry.