Answer:
The correct answer is option C . encuestar a todos los clientes que compren jugos.
Explanation:
In this case, Sharon's best option will be to survey those customers who go to her cafeteria and buy juices.
This will help her know what types of juices people prefer when they go shopping there.
If she did this survey for all customers, some customers who don't even drink juice might respond, and this would lead to a wrong result, as people who would later go buy juice might not be happy.
Given this information we can say that the correct answer is option C.