Statement: There has been a significant drop in the water level of all the lakes supplying water to the city.\nCourses of Action:\nI. Impose a partial cut in municipal water supply to manage the situation.\nII. Appeal through mass media for minimal and prudent use of water by all residents.

Introduction / Context:
Falling reservoir levels threaten urban water security. Immediate demand-side management and public communication are standard responses to extend supplies until recharge or alternative sourcing stabilizes the system.

Given Data / Assumptions:

• All lakes feeding the city show significant decline.
• Short-term demand reduction can avert severe shortages.

Concept / Approach:
A calibrated supply cut (I) directly reduces consumption. Public appeals (II) complement rationing by encouraging behavioral conservation (shorter showers, fixing leaks, off-peak usage, postponing non-essential tasks). Both measures together are proportional and practical.

Step-by-Step Solution:
1) Implement I with transparent schedules, ensuring equitable distribution.2) Implement II: mass messaging, tips, and enforcement against wastage.3) Parallel actions: tanker optimization, borewell regulation, and expedited alternate sources.

Verification / Alternative check:
Urban utilities worldwide pair rationing with communication to manage drought spells.

Why Other Options Are Wrong:
Only I underutilizes public cooperation; Only II may be insufficient without quotas; Either/Neither fail to recognize the complementary nature.

Common Pitfalls:
Unannounced cuts causing inequity; vague appeals without clear targets.

Final Answer:
Both I and II follow.