As per common Indian Standard practice for domestic water-supply design, the peak (maximum) momentary draw-off per capita per minute is taken as which of the following values for the indicated number of users?

Introduction / Context:
Service pipe and storage sizing for small buildings depends on anticipated peak draw-off rates, expressed as per-capita-per-minute values that vary with the number of simultaneous users. Such tabulated values inform plumbing fixture unit calculations and pipe sizing.

Given Data / Assumptions:

• User groups: 5–10, 15, and 20 persons.
• Peak draw-off per capita per minute values are provided.
• Domestic (residential) context under Indian practice.

Concept / Approach:
For smaller groups, the per-capita peak rate is higher (lower diversity), and it decreases as the group size increases (higher diversity). The listed values reflect this: 1.80 L for 5–10 users, 1.20 L for 15 users, and 1.35 L for 20 users (intermediate diversity). All are recognized benchmarks for quick sizing.

Step-by-Step Solution:
1) Understand diversity effect: as users increase, individual coincidence factor drops.2) Apply tabulated per-capita peaks to compute total peak demand for the design group.3) Check pipe sizing against velocity and head-loss criteria using the computed peak.

Verification / Alternative check:
Cross-check with local water authority handbooks where similar per-capita peaks are suggested for preliminary design.

Why Other Options Are Wrong:

• Each of A–C corresponds to a different group size; since all are standard, the comprehensive choice is correct.

Common Pitfalls:

• Applying per-capita peaks from one group size to another without adjustment.
• Ignoring fixture unit method constraints and maximum allowable pipe velocities.

Final Answer:
All the above..