Question

a restaurant that creates a new type of sandwich is using as a method of competition.

Explanation:

In business, especially in marketing and product development, creating a new product (like a new type of sandwich) to compete is related to product differentiation. Product differentiation is a common competitive strategy where a firm creates a unique product to stand out in the market. So the concept here falls under Business, specifically in the subfield of Marketing (or Management/Strategy related to competition). The key is that innovating a product to compete is about differentiating the product from competitors' offerings.

Answer:

product differentiation