Final answer:
Competitive advertising is a form of advertising that firms use when their product enters the growth phase of the product life cycle and other companies begin to enter the marketplace.
Step-by-step explanation:
In the growth phase of a product's life cycle, when other companies begin to enter the marketplace, a form of advertising that firms use is called competitive advertising. Competitive advertising aims to position the firm's product as superior to its competitors' products. It may highlight unique features, benefits, or advantages of the product in order to attract customers and gain a competitive edge in the market.