Which of the following factors does NOT influence rivalry in the yoga and fitness apparel market?

The factor that does not influence rivalry in the yoga and fitness apparel market is the marketing budget. While a marketing budget can certainly impact a company's ability to promote its products and increase brand recognition, it is not a direct influencer of the competitive dynamics within the market itself.

In highly competitive markets like yoga and fitness apparel, what truly drives rivalry among competitors are elements such as product quality and styling, brand image and reputation, and product line breadth. These factors directly affect customer preferences and can differentiate brands from one another. For example, superior product quality may attract more consumers, while a strong brand reputation can foster customer loyalty, both of which intensify competition. Similarly, having a broader product line can help a company meet a wider range of consumer needs and preferences, further heightening rivalry.

Hence, while the marketing budget plays a supportive role in executing strategies to compete, it is less about the inherent competitiveness of the market products and more about the resources allocated for promotion, making it the correct response to the question posed.