Answer: The answer to your question is D: "Heredity is the passing of traits from parent to offspring".
Explanation: If you've ever heard the term "hereditary illnesses", that might give you more insight on this question. Hereditary illnesses are passed from parents, or generations. This means that they are simply only acquired via family and family history.
Heredity in short, just means to be passed through generations, parents, or family.
Why is it not A, B, or C?:
The answer isn't A, because as I already said, heredity is passed on through families, it isn't just acquired as you get older.
The answer isn't B, because reproduction doesn't have anything to do with heredity- other than the fact that heredity things are passed through reproduction.
The answer isn't C, because the process of having an offspring is reproduction, and everything tied to that.
Hope this helps you! (even if it's slightly late)