Answer:
C. The beekeeper is a first-tier supplier of the local restaurant.
Explanation:
The correct definition of a supplier is "a person or organization that provides something that another person or organization needs".
So the answer for the rest of the options is:
A. The local restaurant is a first-tier supplier of the loyal diners.
Wrong. Loyal diners are customers for the restaurant, not suppliers.
B. The busy bees are a first-tier supplier of the local restaurant.
Wrong. Obviously bees are not people or organizations. Somehow we could say that bees are the beekeeper's "workers".
D. The baker is a first-tier supplier of the local restaurant.
Wrong. The baker is a restaurant employee.