Final answer:
A positive externality is seen in an increase in the value of land you own when nearby development is completed, due to the broad community benefits of development, education, and health interventions.
Step-by-step explanation:
The example of a positive externality (additional social benefit) given in the question is d.an increase in the value of land you own when a nearby development is completed. This is because the development enhances the overall attractiveness and utility of the area, which in turn, not only benefits the owner of the newly developed land but also the surrounding property owners through increased land values.
Positive externalities occur when the production or consumption of a product results in benefits to others that the producers or consumers do not have to pay for. Another prominent example of a positive externality is the social benefit gained from investing in education. When the government spends on public education, society gains from a better-educated workforce leading to better health outcomes, lower crime rates, a cleaner environment, and a more stable government.
Positive externalities can also be observed in health interventions like vaccinations, which not only protect the vaccinated individuals but also reduce the spread of illness to others, creating a healthier community overall.