When 2,000 hamburgers per day are produced, the marginal social benefit is $1.50 and the marginal social cost is $1.00. And when 7,500 hamburgers per day are produced, the marginal social benefit is $1.00 and the marginal social cost is $1.50. The efficient production quantity of hamburgers is ________ a day.
选项：

A: more than 7,500
B: 7,500
C: between 2,000 and 7,500
D: 2,000