Statement — The traffic police have installed large notice boards at all major city junctions warning drivers: “Do not use a cell phone while driving, or your license will be impounded.”\n\nAssumptions —\nI. Drivers may ignore the warning and continue to use cell phones while driving.\nII. The traffic police can catch most offenders and actually impound their licenses.

Introduction / Context:
Public warnings paired with penalties function both as deterrents and enforcement notices. For such a warning to be credible, authorities must be able to enforce it. The assumption that drivers will ignore the warning is not necessary; the notice can be aimed at prevention, not merely punishment after noncompliance.

Given Data / Assumptions:

• Intervention: visible notices with a penalty threat.
• I: drivers will ignore the warning.
• II: police can detect violations and impound licenses.

Concept / Approach:
The essential presupposition is enforceability (II). The notice must carry operational credibility. Whether some drivers ignore the warning is not a required assumption for putting up the warning; ideally, all would comply. Thus I is not necessary.

Step-by-Step Solution:

Verification / Alternative check:
Even if most drivers comply, the notice remains sensible; enforcement readiness preserves deterrence credibility.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing the existence of a penalty with an assumption about widespread violation.

Final Answer:
Only Assumption II is implicit.