Why are cast iron (C.I.) pipes commonly preferred in water-supply distribution systems? Select the most appropriate reason from the choices given.

Introduction / Context:Choosing a pipe material for municipal distribution involves balancing cost, ease of installation, and long-term performance. Cast iron (historically) and ductile iron (modern successor) have been widely used for pressurized buried mains due to their structural robustness and reliable joints.

Given Data / Assumptions:

• Buried, pressurized water-distribution environment.
• Standard jointing methods (e.g., spigot-and-socket with gaskets/mechanical joints).
• Corrosion protection (e.g., lining, coatings) is provided as per practice.

Concept / Approach:The selection criteria include capital cost, joint reliability, internal pressure capacity, external load resistance (traffic/surcharge), and expected service life. Cast iron has historically met these requirements, which explains its prevalence in legacy networks and its continued relevance via ductile iron.

Step-by-Step Solution:

Verification / Alternative check:Many cities with century-old C.I. networks still have segments in service, underscoring longevity when protected from corrosion and surge.

Why Other Options Are Wrong:

• Options (a)–(d) each highlight a true advantage; focusing on only one misses the full picture.
• Therefore the comprehensive choice is (e) All of the above.

Common Pitfalls:Ignoring the need for corrosion control; any ferrous pipe without proper protection may suffer premature deterioration.

Final Answer:All of the above