Which of the following best indicates a high-performing, efficient campaign?

A low ACOS (Advertising Cost of Sale) means you're spending less on advertising relative to the sales generated, indicating good cost efficiency. A high ROAS (Return on Ad Spend) means you're getting a significant return for every dollar spent on advertising, signifying strong campaign performance. Together, a low ACOS and high ROAS demonstrate an efficient and highly profitable campaign. The other options represent less efficient scenarios: high ACOS means high ad spend relative to sales, and low ROAS means a poor return on investment.