The three elements most needed in common fertilisers are : A. Sulphur, Phosphorous and Sodium B. Nitrogen, Potassium and Phosphorous C. Phosphorous, Sodium and Nitrogen D. Calcium, Phosphorous and Potassium

Nitrogen is essential for plant growth and development. It is a component of proteins, nucleic acids, and chlorophyll. Nitrogen is also involved in the production of amino acids, which are the building blocks of proteins.

Phosphorus is essential for energy production, cell division, and the formation of cell membranes. It is also a component of nucleic acids, ATP (adenosine triphosphate), and phospholipids.

Potassium is essential for water regulation, photosynthesis, and the production of starch and sugars. It is also involved in the opening and closing of stomata, which are pores on the surface of leaves that allow for gas exchange.

All three of these elements are essential for plant growth and development. They are found in most fertilizers, and they are also available in organic forms, such as compost and manure.