I believe the answer to your question is D
The correct answer is the control variable. For example, if you want to measure how men and women like cats, you would present the same cats to all the people (that;s the constant variables) and gender is your control variable.
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Answer:nobel gaeses are found in the group 18 of the periodic table
Explanation:
Answer:
1)The atomic mass number of an element
2)The relative electronegativity of an element
3) The period of an element
