Final answer:
The activity that does NOT include a positive externality is Gerry walking 3 miles each day for exercise (Option A), as it primarily benefits himself rather than creating a positive impact for others.
Step-by-step explanation:
To answer the question of which activity does NOT include a positive externality, we need to understand what an externality is. An externality is a side effect or consequence of an industrial or commercial activity that affects other parties without this being reflected in the cost of the goods or services involved. Positive externalities occur when the benefits of a product or service extend beyond the individuals who directly utilize it, providing additional benefits to others.
Looking at the options given:
- Gerry walking for exercise has a personal benefit, but it does not create a direct positive externality for others.
- Candy decorating her yard with Halloween decorations provides joy for the neighbors, hence it has a positive spillover.
- Winnie mows the yard of her elderly neighbor for free, which is a kind gesture with a positive impact on the community.
- Craig puts up nets at the basketball court, enhancing the experience for all players, creating a positive spillover.
Therefore, the activity that does NOT include a positive externality is A. Gerry walks 3 miles each day for exercise because it benefits primarily Gerry himself rather than others.