Which of the following is the best definition of the term controlled variables? a) The variable is what is measured or recorded in the experiment. This is the variable in an experiment that the...

Extracted text: Which of the following is the best definition of the term controlled variables? a) The variable is what is measured or recorded in the experiment. This is the variable in an experiment that the researcher can change and b) control A treatment level that is often used for comparison, it is usually zero or a c) natural level. d) The things in an experiment that are kept the SAME for every level of treatment. e) A statement explaining an observation.