I believe the correct response is D. A single variable.
So option B (hybrids have lower fitness than either parent population) is the correct answer.
What is Reinforcement?
Reinforcement is a consequence used in behavioral psychology to strengthen an organism's future behavior when that activity is preceded by a specific antecedent stimulus. This strengthening impact can be quantified as a higher frequency of behavior, a longer duration of behavior, a greater volume of behavior, or a shorter latency.
To learn more about Reinforcement
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A I think but can you get a better picture of the questions
Valves, they are like flaps of muscle that keeps the blood in its place util its ready to be pumped along.
