In the context described, the term instinctual means:

• A. A habit acquired through repetition
• B. A learned, conditioned response
• C. A behavior unique to a single individual
• D. A behavior that manifests in all normal members of a given species

Answer: (D)

The main idea is that instinctual behavior is innate and inherited, not learned. It appears across members of a species and is displayed by all normal individuals without needing experience or practice. That’s why describing an instinctual behavior as something that manifests in all normal members of the species fits best. It distinguishes instinct from learned habits (which come from repetition), and from conditioned responses (which are learned associations), and from behaviors unique to a single individual. So the correct notion is that instinctual actions are universal, species-wide patterns built into biology.