Answer: The answers to the questions by 10 of the friends
Explanation:
The options to the question are:
a. The answers to the questions by the parents of 10 of the friends.
b. The results of a national poll of 1800 students in the same age group as the child.
c. The answers to the questions by 10 of the friends.
d. The answers to the questions by 10 people from the parents office.
From the question, we are informed that a concerned parent wants to determine the amount of time spent on the phone by her child's friends. The sample that is likely to bias the results of the study by reporting less than the actual time is the answers to the questions by 10 of the friends.
This is because since the questions are being asked from her friends, there'll be bias as the friends won't want to give the exact time used on phone, hence, they'll hold back some information.