Optimization levers can help advertisers set benchmarks for which key measures to help achieve campaign results?

The correct answer is Viewability and completion rate targets. Optimization levers are crucial for helping advertisers set benchmarks to measure the effectiveness of their video ad campaigns. Specifically, viewability and completion rate targets are key indicators of how well the ads are engaging the audience. Viewability refers to the percentage of an ad that is visible to the user, while completion rate measures the proportion of viewers who watch the video ad in its entirety. Setting these targets allows advertisers to ensure that their ads are being seen by the right audience and that the content is compelling enough to hold viewers' attention until the end. By focusing on these metrics, advertisers can optimize their campaigns to improve engagement and ultimately drive better campaign results.