Why is phosphorus considered an essential nutrient for plants?

Phosphorus is considered an essential nutrient for plants primarily because it plays a crucial role in the structure and function of several key biochemical compounds, including DNA, RNA, and adenosine triphosphate (ATP). DNA and RNA are vital for genetic information and protein synthesis, both of which are fundamental processes for plant growth and development. ATP is the primary energy carrier in cells, enabling various metabolic processes, including photosynthesis and respiration.

While phosphorus does contribute to other aspects of plant health and development—such as root development and overall plant vigor—its critical involvement in genetic material and energy transfer pathways is what distinctly qualifies it as an essential nutrient. This significance underlines the importance of phosphorus in plant nutrition and its overall contribution to plant life cycles, making option C the correct choice in this context.