Whenever Adrian plays his favorite game he always gets a higher score if he plays while listening to music . he wants to know if listening to music while playing a video game affects other kids as well . he decides to test all the boys in his class what should Adrain do to avoid experimental bias ?
A. only test boys who usually play video games .
B. only test the boys who like video games .
C. include girls in the experiment .
D. include the teacher in the experment.

Question

Whenever Adrian plays his favorite game he always gets a higher score if he plays while listening to music . he wants to know if listening to music while playing a video game affects other kids as well . he decides to test all the boys in his class what should Adrain do to avoid experimental bias ? 
A. only test boys who usually play video games .
B. only test the boys who like video games .
C. include girls in the experiment .
D. include the teacher in the experment.