Final answer:
The strong emotional reaction when entering a restaurant and being reminded of your grandmother's kitchen is due to your sense of smell. The olfactory system is closely connected to the limbic system and hypothalamus in the brain, where smells become associated with long-term memory and emotional responses.
Step-by-step explanation:
The strong emotional reaction you experience when entering a restaurant and being reminded of your grandmother's kitchen is most directly due to your sense of smell. The olfactory system, which is responsible for our sense of smell, is closely connected to the limbic system and hypothalamus in the brain, where smells become associated with long-term memory and emotional responses.