Which of the following best defines a trait?

• A. Any characteristic of an animal that can take on different values
• B. A fixed constant
• C. A behavior only
• D. A measurement of nutrition

Answer: (A)

A trait is any characteristic of an organism that can be observed or measured and can vary among individuals. This includes things like color, height, milk yield, enzyme activity, or behaviors. The essential idea is variation: a trait exists because individuals differ in that characteristic. A fixed constant wouldn’t qualify as a trait since it doesn’t vary. A behavior is one possible type of trait, but traits aren’t limited to behavior. A nutrition measurement is a specific example of a trait, not the general definition. So the statement that a trait is any characteristic that can take on different values best captures the concept.