_______ is a measurement and analytics solution that provides a way for advertisers to measure the aggregated, total impact of their ad tactics on shopping activities on Amazon.com or third-party websites, while campaigns are still mid-flight.

The correct answer is Omnichannel Metrics, as this measurement and analytics solution allows advertisers to assess the aggregated, total impact of their advertising tactics on shopping activities across both Amazon.com and third-party websites, even while campaigns are still running. This capability provides real-time insights into how various ad strategies influence customer behavior and purchasing decisions, enabling advertisers to make informed adjustments to optimize performance. By leveraging Omnichannel Metrics, advertisers can gain a comprehensive understanding of their campaigns' effectiveness across multiple channels, ensuring a more cohesive and impactful advertising approach.