Analogy — “Tree : Root :: Smoke : ?”. Choose the option that stands to smoke as a generative source/cause (parallel to root as a generative base for the tree).

Introduction / Context:
Roots are foundational to a tree — the source from which it anchors and draws sustenance. By analogy, we seek the common cause/source that gives rise to smoke. Among everyday causes, “fire” is the standard, primary source of smoke in general contexts.

Given Data / Assumptions:

• “Tree : Root” treats root as a fundamental source/support for the tree.
• We need a similarly foundational generator for smoke.
• The relation should be causal/generative, not merely associative or a pathway.

Concept / Approach:
Distinguish “cause/source” from “container,” “path,” or “by-product.” While cigarettes can produce smoke, “fire” is the canonical, broad cause that mirrors the generality of “root.”

Step-by-Step Solution:

Verification / Alternative check:
In standard logical analogies, generic cause is preferred over a specific instance, preserving parallelism with “root” rather than a particular brand/source.

Why Other Options Are Wrong:
They are either specific instances, pathways, or related effects, not the fundamental cause.

Common Pitfalls:
Choosing a specific example (cigarette) instead of the general cause (fire).

Final Answer:
Fire