Public goods are non-excludable and non-rivalrous

Steps:

• Define a public good as a resource that is non-excludable (no one can be prevented from using it) and non-rivalrous (one person's use doesn't reduce availability for others).
• Evaluate each option: check excludability (can providers exclude non-payers?) and rivalry (does consumption by one affect others?).
• Compare how well each fits both criteria, identifying the closest match.
• Select the option that best satisfies both properties.

Why C is correct:

• Street lighting is non-excludable (impossible to prevent non-payers from benefiting) and non-rivalrous (one person's illumination doesn't diminish it for others), per the standard economic definition of public goods.

Why the others are wrong:

• A. Electricity: Excludable, as providers can disconnect non-payers.
• B. Health services: Rivalrous, as a doctor's time is limited and serves one patient at a time.
• D. Water supply: Excludable, as utilities can shut off service to non-payers.

Final answer: C