What are the factors kept the same in an experiment called?

Correct answer: Controlled variables

The direct answer is B: the factors kept the same are controlled variables. In a fair experiment, usually one factor is deliberately changed, the response is measured, and other important conditions are kept constant. For example, when testing the effect of fertiliser on plant growth, the fertiliser may be changed, height may be measured, and pot size, soil type, water and light should remain the same. Option B is correct because these fixed conditions prevent an unfair comparison. Option A, observations, are things noticed or measured; they are not necessarily kept constant. Option C, conclusions, are statements made after studying results. Option D, hypotheses, are testable predictions made before or during an investigation. Thus a controlled variable is a condition held steady, not a record, final statement or prediction. Exam cue: changed factor is independent, measured result is dependent, and held-constant factor is controlled.