Social cost as total societal burden

Steps:

• Recall that social cost includes both private costs borne by producers and external costs affecting society.
• Identify private costs as direct expenses like wages and materials in coal production.
• Recognize external costs as unaccounted harms like pollution and health impacts from coal mining.
• Combine these to define social cost as the full economic impact on society.

Why D is correct:

• Social cost is defined in economics as private costs plus external costs, capturing the total societal expense beyond just producer outlays.

Why the others are wrong:

• A describes net social benefit, not cost.
• B covers only environmental externalities, ignoring private costs.
• C refers to government subsidies, which are a fiscal transfer, not the full social cost.

Final answer: D