Is a posttest method used in broadcast commercials that traces the behaviors of consumers from a television set to a supermarket checkout counter.
a. contextual testing
b. bipolar tracking
c. the burke follow-up test
d. the starch test single-source tracking

"Single-source tracking" is the "posttest method" used in "broadcasting commercials".

Explanation:

Single- source tracking is a post test which means this test is taken after a specific advertisement is out in the market. This method is basically used to know the reactions, and views about the products or services intended through those commercials. Consumers present in the television set or any supermarket checkout counter or any place where they go through this test, where the assigned people look after the consumers to know their reaction by tracing it from their face.

tbh idk same thing here

the telephone is the answer