Public Goods and Market Failure

Steps:

• Identify the role of government in mixed economies: addressing market failures where private markets fail.
• Recall public goods definition: non-excludable (can't prevent non-payers from using) and non-rivalrous (one's use doesn't reduce availability).
• Recognize the free-rider problem: private firms can't profitably provide these goods as people benefit without paying.
• Conclude government steps in to supply them for societal benefit.

Why D is correct:

• Public goods are non-excludable, so private firms face free-rider issues and can't charge users, per economic theory of market failure.

Why the others are wrong:

• A: Governments don't always provide cheaper; efficiency varies by case.
• B: Governments consider social costs/benefits, not just private ones.
• C: Preventing monopolies involves regulation, not direct provision of public goods.

Final answer: D