Question

Why do we want to test one variable at a time? a. Because it is hard to setup a data table with more b. It is what has always been done c. To know what is causing the changes d. No one really knows​

Answer 1

C

Step-by-step explanation:

If you have more than one variable then you wont know which variable caused the change. Hope this helped, if it did give it a thanks or whatever.