Norman thinks that the brain function of students suffers when they receive less sleep. he predicts that students who get less sleep before an exam will receive lower test grades. to investigate his idea, he tests two groups of chemistry students. group 1 receives four hours of sleep, while group 2 receives the recommended eight hours of sleep the night before the exam. both groups consume the same foods before testing. they then take the same exam in the same room. what experimental factors could have been a possible source of error in norman's investigation?

a. the food students consumed before the exam
b. the amount of sleep students received before the exam
c. the grades students earned on their exam
d. the temperature and light of the testing room

Option A and D

Explanation:

This experiment is about studying the effect caused on test grades of the student by the number of hours of sleep taken by them before the exams. Therefore, there is least chance of making a mistake in the variable "hour of sleep" as it is the main independent variable whose impact is to be studied on grades.  

Also grades earned are the dependent variable which is easily measurable hence chances of making mistakes in this variable are also less.  

However, the light and temperature of the room in which students were allowed to sleep may not be as per the requirement of all the students, therefore some kind of error may occur due to this variable.  

Likewise the food provided to the students may not be as per the requirement and likeliness of each and every student. Hence, it also becomes a source of error.

to this one it would be receptive field