Which of the Following Statements About a Well-Maintained Yard Best

Which of the following statements about a well-maintained yard best conveys the general nature of the externality?

A) A well-maintained yard conveys a positive externality because it increases the home's market value.
B) A well-maintained yard conveys a negative externality because it increases the property tax liability of the owner.
C) A well-maintained yard conveys a positive externality because it increases the value of adjacent properties in the neighborhood.
D) A well-maintained yard cannot provide any type of externality.