A one-party system helps to prevent

Analyze the question: It asks what a one-party system helps to prevent. So we need the option that is a problem a one-party system would reduce or avoid, not a benefit it provides.

Explain the concept: In a one-party system, only one political party is legally allowed to govern, with no opposition parties. Commonly cited advantages in Government textbooks include:

• Quick decisions, because there is no opposition to delay policy.
• Strong, stable leadership, because power is concentrated in one party.
• National unity, because fewer political divisions exist.
• Avoiding waste of resources, because there are no costly rival campaigns, multiple party structures, or repeated contests between parties.

Solution, option by option:

• A. Quick decision: A one-party system promotes quick decisions, so it does not prevent them.
• B. Strong leadership: It tends to produce strong leadership, so it does not prevent it.
• C. Stable leadership: It tends to encourage stability, so it does not prevent it.
• D. Economic waste: Running many parties and competitive elections is expensive. A one-party system avoids duplicating party machinery and campaign spending, and it limits delays from endless debate. So it helps prevent economic waste.

Answer: The option that fits "helps to prevent" is D. economic waste.

Exam tip: When a question says "helps to prevent" or "avoids," look for the negative word in the options (waste, delay, conflict, instability). The positive options (quick, strong, stable) are usually things the system promotes, which makes them the wrong choice here.