The graph below shows the market for honey. Producing honey carries with it a positive externality because the honey bees play an important role in the pollination of plants, promoting agricultural productivity and environmental health. Most consumers don't take this benefit into account when they are in the grocery store deciding whether or not to buy honey.

A. 15 million honey bees

B. 5 million honey bees

C. 7 million honey bees

D. 3 million honey bees

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