A variable whose value is determined by the model of which it is a part is termed______.
A. constant
B. endogenous
C. exogenous
D. independent
If lighthouses are public goods, then free markets would______.
A. create a lighthouse monopoly
B. provide the optimal number of lighthouses
C. provide more than the optimal number of lighthouses
D. provide less than the optimal number of lighthouses
微信支付 
支付宝支付