A physics instructor believes natural light improves learning and tests 25 randomly selectedstudents under 2conditions,natural light and artificial light. A learning task is given under each conditionand scored as number correct. A difference score is computed between the two tasks.What condition below will you assess for the appropriate statistical test for this study?

	A.	Does the difference score have a normal distribution?
	B.	Are expected cell sizes greater than 5?
	C.	Do the conditions have similar standard deviations and normal distributions?
	D.	Does the relationship appear linear?