What is the value of running a true A/B test with campaign experiments?

A/B tests can help marketers understand if their trial campaign drove user action that wouldn’t have occurred otherwise.
In an A/B test, trial campaigns run at the same time as the original campaign, controlling for external factors (e.g. seasonality) that may otherwise bias results.
An A/B test runs one campaign at a time, allowing a true ramp-down period between each testing timeframe to declutter results.
An A/B test is designed to test multiple variables at one time, allowing advertisers to learn and quickly adjust their campaigns based on findings.

The correct answer is:

In an A/B test, trial campaigns run at the same time as the original campaign, controlling for external factors (e.g. seasonality) that may otherwise bias results.