Answer:
D- works like an instinct
Step-by-step explanation:
Fear is one of the most basic human emotions. It is programmed into the nervous system and works like an instinct. From the time we're infants, we are equipped with the survival instincts necessary to respond with fear when we sense danger or feel unsafe. You don't learn to feel fear (so not A), it isn't necessarily not helpful (so not B), and fear is something built into our system (not C).