Arrange the construction-related items in the correct logical order to form a usable room, starting from the very first activity to the final outcome. (a) Windows (b) Walls (c) Floor (lay slab/finish) (d) Foundation (footings/base) (e) Roof (f) Room (complete, habitable space) Choose the correct sequence from first to last.

Introduction / Context:
This problem asks you to order parts of a building process in a way that respects real-world dependencies. A room becomes usable only after structural and enclosure steps happen in a sensible sequence that construction sites follow for safety, accuracy, and cost control.

Given Data / Assumptions:

• Foundation supports all loads above.
• Floor slab is cast/laid on or tied to the foundation.
• Walls rise off the floor/foundation and define openings.
• Windows are fitted into prepared wall openings.
• Roof is installed to weatherproof the enclosure.
• “Room” denotes the finished, habitable space result.

Concept / Approach:
Use prerequisite logic: without a foundation nothing can stand; the floor ties into the base; walls stand on the structural base; windows cannot be fitted before walls exist; roof usually caps the enclosure; only then do we have a completed room. Hence: Foundation -> Floor -> Walls -> Windows -> Roof -> Room.

Step-by-Step Solution:
Step 1: Lay foundation (d).Step 2: Construct/finish the floor (c).Step 3: Build walls (b).Step 4: Install windows (a).Step 5: Add the roof (e).Step 6: The result is a completed room (f).

Verification / Alternative check:
Site method statements and standard building sequencing place foundations and slabs before masonry, then openings, then roofing. This prevents rework and structural instability.

Why Other Options Are Wrong:

• d, b, c, a, e, f: Walls before floor complicates alignment and services.
• d, c, b, e, a, f: Roof before windows leaves openings unsealed and is atypical.
• d, b, a, c, e, f: Windows cannot precede floors and finished wall structure.
• d, c, e, b, a, f: Roofing before walls is impossible for most structures.

Common Pitfalls:
Mixing up “what is visible first” with “what must come first.” Foundations and slabs are less visible later but absolutely precede everything. Window fitting always depends on finished openings.

Final Answer:
d, c, b, a, e, f