The correct option is B Potassium
There are two types of nutrients that absorbed by the plants- macronutrient and micronutrient. Macronutrients are the nutrients that absorbed in the large quantity such as potassium, sulphur, calcium, nitrogen, phosphorus, magnesium etc. Whereas the nutrients required in small amount is called as micronutrients such as manganese, boron, cobalt, molybdenum, zinc, iron, copper and iodine. Thus, the correct answer is option C.