Common uses of mild steel in construction: which selection best reflects where mild steel is employed? (Consider structural members, small-diameter water pipes, and compression members.)

Introduction / Context:
Mild steel (low-carbon steel) is widely used in construction due to its weldability, ductility, and cost-effectiveness. The question tests recognition of typical application domains in building and infrastructure projects.

Given Data / Assumptions:

• Mild steel offers adequate yield strength with good ductility.
• It is compatible with welding, bolting, and standard fabrication methods.
• It is supplied as rolled sections, plates, and pipes.

Concept / Approach:
Because of its balanced mechanical properties, mild steel is used across structural framing (beams/girders), services (water pipes), and compression members (columns/struts), often in grades optimized for yield strength and toughness. Therefore, the most accurate single answer is the inclusive 'All of the above'.

Step-by-Step Solution:

Verification / Alternative check:
Design manuals and steel codes list low-carbon steel grades for a broad range of building members, with higher-strength alloys reserved where required by design.

Why Other Options Are Wrong:

• Any single application understates the broad utility of mild steel in construction practice.

Common Pitfalls:
Assuming high-carbon or alloy steels are always superior; in many cases, ductility and weldability of mild steel govern selection rather than peak strength alone.

Final Answer:
All of the above