Statement — Smoking cannabis (from the hemp plant) causes illnesses similar to cigarette smoking (e.g., heart disease and cancer) and is far more dangerous than tobacco for mental health.\nQuestion — Which conclusion necessarily follows?

Introduction / Context:
The statement directly compares health effects of cannabis and tobacco. We must decide which conclusion is a strict logical consequence.

Given Data / Assumptions:

• Bodily (somatic) harms: cannabis ≈ cigarettes.
• Mental-health risk: cannabis > tobacco.
• No claim about usage trends or population uptake.

Concept / Approach:
Conclusions must be entailed, not merely plausible. A prediction about a “surge” in mental illness depends on future usage and other determinants; a comparative statement about effects follows immediately.

Step-by-Step Solution:

Verification / Alternative check:
Even with stable or falling cannabis use, II remains true; I hinges on usage patterns and public-health context.

Why Other Options Are Wrong:
Any option endorsing I imports epidemiological projections not in the stem.

Common Pitfalls:
Conflating comparative hazard with predicted incidence.

Final Answer:
if only conclusion II follows