• By testing multiple variables at a time, an A/B test gives advertisers information they can use to adjust their campaigns quickly based on insights.
• By revealing whether their trial campaign drove user action that wouldn’t have taken place otherwise, an A/B test gives insights into user behavior.
• By running a single campaign at a time, an A/B test allows for a true ramp-down period between each testing period so that results can be decluttered.
• By running concurrently with an original campaign, a trial campaign controls for external factors, like seasonality, that might otherwise bias results.

The correct answer is: By running concurrently with an original campaign, a trial campaign controls for external factors, like seasonality, that might otherwise bias results.

Explanation: Running a true A/B test with campaign experiments has significant benefits for optimizing your digital marketing efforts. By running a trial campaign concurrently with your original campaign, you can control for external factors such as seasonality that might bias your results. This simultaneous execution allows for a fair comparison, helping you understand whether proposed changes will improve your campaign performance or not. It’s a reliable way to test changes before fully implementing them in your campaign strategy.