Which of the following is/are true about macronutrients?
a) Plants require them in relatively large amounts
b) Sometimes plants require them in relatively large amounts, but some other times, plants need them in very small amounts
c) They are chlorine, iron, manganese, boron, zinc, copper, nickel
d) They are carbon, oxygen, hydrogen, nitrogen, phosphorous, sulfur, potassium, calcium, and magnesium