1. Each task in the kitchen requires a different height for optimal ergonomics:
- Task 1 (Washing utensils): Should be higher to avoid bending, keeping the sink at elbow height.
- Task 2 (Rolling chapati): Should be at a medium height to allow comfortable rolling, slightly below elbow level.
- Task 3 (Chopping vegetables): Should be at a slightly lower height than Task 2 for better visibility and precision.
2. Keeping all tasks at the same height would lead to discomfort and inefficiency for certain tasks. Hence, options \(A\), \(B\), and \(C\) are incorrect.
Conclusion: The most beneficial arrangement is \(D\) (all three tasks at different heights).