Yellowing and brown end of leaf is because of deficiency of:

Explanation

The correct answer is Potassium. Potassium is crucial for numerous plant processes, including water regulation and enzyme activation. A potassium deficiency often results in yellowing and browning of leaf margins and tips, a symptom not typically associated with other nutrient deficiencies. While nitrogen deficiency does cause yellowing, it affects older leaves more uniformly rather than just the edges. Sodium is not an essential nutrient for most plants, and iron deficiency results in yellowing between the veins but not browning at the leaf edges.