Josiah installed a metal sculpture in his front yard. A positive externality arises if the sculpture a. creates a safety hazard for neighborhood children. b. increases the value of Josiah's home. c. increases the value of other properties in the neighborhood. d. is visually unappealing to Josiah's neighbors.

C. increases the value of other properties in the neighborhood.

Explanation:

A positive externality occurs when the action of an economic agent brings about a benefit to others who aren't involved in the action.

In this case, the positive externality with regards to Josiah installing a metal sculpture in his front yard will be the increase in the value of other properties in the neighborhood.

Option A is incorrect as the creation of a safety hazard for neighborhood children is a negative externality. Option B is wrong as Josiah enjoyed the benefit and not a third party. Option D is a negative externality. Therefore, the correct option is C.