Lane and Riley Are the Only Two Residents in a Neighborhood,and

Lane and Riley are the only two residents in a neighborhood,and they share the same driveway.They would like to have the driveway paved.The value of the paved driveway is $1500 to Lane and $1000 to Riley.Irrespective of who pays for the paving both people will benefit from it.
Relative to the two-person scenario described,if a large number of people share the driveway,the joint purchase of paving is _______ and the ________ emerges.

A) impossible;tragedy of the commons
B) less costly;maximum economic efficiency
C) more likely to be accomplished;free-rider problem
D) more difficult;free-rider problem