Lila Shares a House with Two Other People

Lila shares a house with two other people.She is a concert pianist and often practices at home.One roommate enjoys listening to her practice,but the other does not.For the roommate who enjoys listening to Lila play,this is an example of ________; for the other roommate,it is an example of ________.

A) the tragedy of the commons; the third-party problem
B) a positive externality; a negative externality
C) a positive externality; the free-rider problem
D) the free-rider problem; the tragedy of the commons
E) a negative externality; the tragedy of the commons