Xavier wants to optimize his Website Conversions campaign to generate more conversions at a more efficient cost. Which of the metrics should he primarily focus on?

To optimize for more conversions at a more efficient cost, Xavier should primarily focus on Cost Per Conversion. This metric directly measures the cost incurred for each conversion achieved, making it the most relevant indicator for cost efficiency in a conversion-focused campaign. A lower Cost Per Conversion signifies a more efficient campaign. While Conversions is important for tracking volume, it doesn't inherently tell you about cost efficiency. Cost Per Click (CPC) measures the cost of each click, which is a step towards conversion but not the final outcome. A low CPC doesn't guarantee a low Cost Per Conversion if the click-to-conversion rate is poor. Reach indicates how many unique users saw the ad, which is a top-of-funnel metric and not directly tied to conversion efficiency.