Which metric would best reflect success in driving awareness?

The selected answer Impressions is correct because impressions are the most appropriate metric to reflect success in driving awareness. Impressions measure how often an ad is displayed to a user, making it a direct indicator of the reach and visibility of the campaign. In awareness campaigns, the goal is typically to increase brand recognition and introduce the product to as many potential customers as possible, which is best measured by how frequently the ad is shown to the target audience. While metrics like "add to cart" or "clicks" are important for later stages of the funnel, they are not directly related to the initial goal of building awareness.