Concept:The diagram shows a root nodule containing nitrogen-fixing bacteria, which supply nitrogen to the plant.
Explanation:Root nodules of leguminous plants contain bacteria such as
Rhizobium.
These bacteria carry out symbiotic nitrogen fixation.
They convert atmospheric nitrogen into forms the plant can use.
So the root system already obtains enough nitrogen from the nodules.
Therefore, a nitrogenous fertilizer will not be required for this root system.
Among the options, ammonium sulphate,
(NH4)2SO4, is a nitrogenous fertilizer.
Potassium sulphate is still needed because it supplies potassium.
Rhizobium is a bacterium, not a fertilizer, and
Azotobacter is another nitrogen-fixing bacterium.
Answer:B. Ammonium sulphate
