Analogy — “Good : Bad :: Roof : ?”. Select the option that stands as a standard opposite/counterpart to “roof,” paralleling the antonym pattern.

Introduction / Context:
“Good : Bad” establishes an antonym relationship. The second pair must preserve this opposition pattern in a structural/architectural context. In a room/house, “roof” and “floor” represent opposing upper and lower boundaries.

Given Data / Assumptions:

• The target is an opposite/counterpart, not just any related structural term.
• Common architectural understanding is assumed.

Concept / Approach:
Identify which element is the natural counterpart to a roof in vertical opposition within a built space.

Step-by-Step Solution:

Verification / Alternative check:
“Ceiling” is the inner lower face of a roof/slab, yet not the opposite in the way “floor” is; the opposite boundary is “floor.”

Why Other Options Are Wrong:
They are structures or surfaces but do not form the canonical vertical opposite to “roof.”

Common Pitfalls:
Choosing “ceiling” due to proximity; the antonymic counterpart is “floor.”

Final Answer:
Floor