Concept:Potassium deficiency appears first on older leaves, mainly at the tips and margins.
Explanation:Potassium is a mobile nutrient inside the plant.
When potassium is lacking, the plant moves it from older leaves to younger growing parts.
As a result, the older leaves of cereal crops show the first visible symptoms.
The leaf tips and margins turn brown and die, creating a scorched or burned appearance.
This browning begins at the tips and edges, then spreads inward.
Yellowing of younger leaves is more typical of nitrogen or sulfur deficiency.
Purpling of leaves is commonly linked to phosphorus deficiency.
White irregular spots are not the classic sign of potassium shortage.
Thus, the typical indicator of potassium deficiency is browning from the tips and margins.
Answer:A. browning of leaves from the tips and margins