In measurement and estimation for building services, which of the following statements regarding water-supply pipe items is correct: separate measurement of trench-laid versus wall-fixed pipes, inclusion of cutting through walls/floors with the pipe item, classification of pipes by size/quality, and explicit specification of jointing/fixing method?

Introduction / Context:
Accurate quantity take-off for water-supply work follows standardized measurement rules so that tenders, billing, and cost control remain consistent. This question checks your grasp of how pipeline items are segregated, what incidental works are included, and how specifications like size, material, and jointing methods are recorded for clarity in civil engineering estimation.

Given Data / Assumptions:

• The item pertains to potable/service water-supply piping.
• Installations may be trench-laid (buried) or surface-fixed (on walls/ceilings).
• Openings through walls/floors are required along pipe routes.
• Standard measurement conventions per common schedules of rates and IS methods are followed.

Concept / Approach:
Measurement rules separate items by how and where the pipe is installed because resources, supports, and making good differ. Incidental operations like cutting chases or holes and making good are included with the pipe laying/fixing item to avoid double counting. Pipes are always classified by nominal size and material/quality (e.g., GI Class B/C, CPVC SDR rating), and the method of jointing (threaded, welded, solvent-cemented, flanged) must be explicitly specified because it affects labour, fittings, and durability.

Step-by-Step Solution:
1) Identify work location: trench-laid vs wall/ceiling-fixed → measure separately due to different accessories and labour.2) Include associated operations: cutting through masonry or slabs and later making good are commonly included with the pipe item.3) Classify the pipe: record size (e.g., 25 mm nominal bore) and quality (material grade/class).4) Specify jointing/fixing: state threading/welding/solvent cement, clamps/hangers spacing, and anchors.

Verification / Alternative check:
Cross-check with a schedule of rates or method-of-measurement standard: each of the listed statements appears as a foundational rule to keep items unambiguous and comparable across bidders and bills.

Why Other Options Are Wrong:

• Options A–D are all true individually; choosing any single one omits other essential rules.

Common Pitfalls:

• Lumping trench and wall runs together, which obscures supports and restoration costs.
• Omitting making-good after cutting, leading to variations later.
• Failing to specify jointing method, causing quality and pricing disputes.

Final Answer:
All the above.