Which nutrients are considered macronutrients necessary for plant health?

The nutrients that are classified as macronutrients essential for plant health include nitrogen (N), phosphorus (P), and potassium (K). These elements are vital because they are required in larger quantities compared to other nutrients. Nitrogen is crucial for the synthesis of amino acids and proteins, phosphorus plays a key role in energy transfer and the formation of DNA and RNA, while potassium is important for osmoregulation and enzyme activation.

The other groups of nutrients listed contain essential elements for plant growth but do not fall under the category of macronutrients. For instance, the first option lists micronutrients, which are needed in smaller amounts, while the third option includes elements that, although necessary for plant growth, such as carbon (C), oxygen (O), and hydrogen (H), are not technically classified as macronutrients in the context of nutrient management, as they are primarily sourced from air and water rather than the soil. Thus, option B identifies the core macronutrients integral for robust plant growth and development.