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.” Assumptions — I. Drivers may ignore the warning and continue to use cell phones while driving. II. 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.