If an advertiser uses Google's phone call conversion tracking feature, how are the calls tracked to their account?

The selection is correct because Google's phone call conversion tracking relies on a dynamically created Google forwarding number that replaces the advertiser's standard business phone number in their ads or on their website. When a user interacts with an ad and subsequently calls this unique, temporary number, the call is routed through Google’s system before being connected to the advertiser's actual business line. This intermediary step allows Google to capture essential measurement data—such as the call’s start time, duration, and the specific ad or keyword that triggered the interaction—enabling the advertiser to attribute the phone call as a conversion based on their predefined criteria (e.g., a call lasting longer than 60 seconds).