A botanist claims to have discovered a new macronutrient required for plant growth. Most of this scientist's colleagues are skeptical of her claim. Why might they consider it unlikely?
A
All the nutrients required for plant growth have already been found.
B
It is very difficult to prove that a plant needs a certain nutrient.
C
Plants need thousands of nutrients; a new one is not significant.
D
Plants manufacture their own macronutrients.
E
Any nutrient needed in large amounts (macronutrient) has probably been noted already.