Assume that the demand for graduation merchandise is uniformly distributed between 4000 and 7500. The university store plans to charge $20 per item, while it costs the store $10 per item. After the graduation weekend, the unsold merchandise can be recycled by the university store by getting $6 per item from the recycler. How many items of merchandise should the store stock in order to optimize the profit?
a.5000
b.6500
c.7000
d. None of these