Brand Impression Share is the key Sponsored Brands report for measuring awareness campaign performance and understanding your brand’s share of top-of-search visibility on Amazon.

• Advertised purchases
• Matched target
• Brand Impression Share

The correct answer is: Brand Impression Share

Explanation: For campaigns with an awareness goal, the Brand Impression Share report in Sponsored Brands is the most relevant for reviewing performance. This report tracks the percentage of top-of-search impressions your ads receive compared to the total available impressions for your brand terms. It shows how well you’re capturing visibility versus competitors—letting you understand your share of voice and the effectiveness of your ad efforts in building brand awareness.

Reference:  https://advertising.amazon.com/library/guides/sponsored-brands-what-to-know