Which of the following organic manures has the narrowest C/N ratio?

Answer: Option C

Groundnut cake from the following organic manures has the narrowest C/N ratio. A carbon-to-nitrogen ratio (C/N ratio or C : N ratio) is the ratio of the mass of carbon to the mass of nitrogen in organic residues.
Groundnut cakes are suitable for all types of crops. Nutrient content percentage % ratio for this manure is, N : P : K = 7.3 : 3 : 2.2. This helps in improving the health of plants and thus enhances the crop yield. It is often used to boost the growth of fruit, flower and vegetable crops.