Arrange the following steps in the correct order to illustrate the positive externalities in consumption from planting trees in a neighborhood: A) Homeowners plant trees, B) Neighbors enjoy improved air quality and aesthetics, C) Increased property values in the area, D) Local government considers subsidies for tree planting.

To illustrate the positive externalities in consumption from planting trees in a neighborhood, we start with homeowners planting trees (A). Once the trees are planted, neighbors benefit from improved air quality and the beauty of their surroundings (B). This enhancement leads to increased property values in the area, as homes become more desirable (C). As a result of these benefits, the local government may consider offering subsidies to encourage more tree planting (D). This sequence shows how one action can create a ripple effect of positive outcomes for the entire community.