The correct option is B Calcium
Based on the quantitative requirements of mineral elements by plants, nutrient elements have been divided into 2 broad categories:
1. Macronutrients: These are present in plants in excess of 10 mmole per kg of dry weight. They are carbon, oxygen, hydrogen, calcium, magnesium, nitrogen, phophorus, sulphur, potassium.
2. Micronutrient: These are present in plants in quantities less than 10 mmol per kg of dry weight. They are manganese, iron, zinc, copper, nickel, molybdenum, boron, chlorine.