Answer: A gene that exhibits multiple phenotypic expression.
I don't know witch definition you mean, but here: https://www.google.com/search?q=google+dictionary&rlz=1C1CHBF_enUS871US871&oq=google+dic&aqs=chrome.0.0j69i57j0l6.3972j0j7&sourceid=chrome&ie=UTF-8#dobs=blowout
Answer:
The length of the two wires
Explanation:
A control variable is what you keep the same through the whole experiment so therefore it could be both length and diameter
Answer: The 3rd one, answer C