¿Cuáles son las dos variables que utiliza la subasta para determinar qué anuncio se mostrará?

The two primary variables an ad auction uses to determine which ad to show are Cost-Per-Click (CPC) Bid and Relevance. The CPC bid is the maximum amount an advertiser is willing to pay for a click, directly influencing their competitiveness. Relevance assesses how closely the ad creative and landing page align with the user's search query or browsing context, ensuring a good user experience. "Ad type, budget" is incorrect because ad type is a format, not an auction variable, and while budget is important for overall campaign pacing, the bid is the direct input to the auction. "Pixels, CPC bid" is incorrect because pixels are tracking mechanisms, not auction variables. "Ad spend, relevance" is incorrect because ad spend is the total amount spent over time, not a direct input to a single auction instance like a bid is.