The land treatment of sewage is suitable, when
- Athe overall rainfall is very high
- Bthere is no river or natural water courseCorrect
- Cthe quantity of sewage is less
- Drivers usually run full during summer
Solution
Concept
Conditions favouring disposal on land
Step-by-step solution
1. Land treatment is preferred where dilution in a river is not available, e.g. no river or natural watercourse nearby. 2. Heavy rainfall or full rivers favour dilution instead.
Explanation
Sewage is disposed on land when a watercourse is absent or has insufficient dilution capacity, provided suitable soil and land are available.
Why the other options are wrong
High rainfall makes land treatment difficult. A small quantity of sewage does not by itself determine the method. If rivers run full in summer, dilution is possible.
Shortcut
No river → land disposal.
Common mistake
Choosing small quantity of sewage.
Correct answer: B) there is no river or natural water course