Externalities are the positive or negative impacts of an asset that are not reflected in its financial costs.
Why A (Impact on the environment) is correct:
Infrastructure assets (e.g., roads, dams, power plants) create environmental and social externalities, such as:
Air pollution from transportation projects.
Habitat destruction from hydroelectric dams.
Noise pollution from airports.
Why not B or C?
B is incorrect—technical issues (e.g., equipment failure) are not classified as externalities.
C is incorrect—externalities originate from the asset itself, not external factors.
References:
OECD: Managing Environmental Externalities in Infrastructure Projects (2022)