Question

What is the most important reason to control the conditions of an experiment?
A) to make the experiment easier to repeat
B) to reduce the amount of data that must be recorded
C) because this is necessary for graphing the data
D because this is necessary for the data to be valid

Answer 1

OK so basically you want to control the experiment because you want to make sure that the data to be valid.

Answer 2

Answer;  

Because this is necessary for the data to be valid