Although spinach is rich in calcium, it also contains large amounts of oxalic acid, a substance that greatly impedes calcium absorption by the body. Therefore, other calcium-containing foods must be eaten either instead of or in addition to spinach if a person is to be sure of getting enough calcium. Which of the following, if true, most seriously weakens the argument above
A．Rice, which does not contain calcium, counteracts the effects of oxalic acid on calcium absorption.
B．Dairy products, which contain even more calcium than spinach does, are often eaten by people who eat spinach on a regular basis.
C．Neither the calcium nor the oxalic acid in spinach is destroyed when spinach is cooked.
D．Many leafy green vegetables other than spinach that are rich in calcium also contain high concentrations of oxalic acid.
E．(E) Oxalic acid has little effect on the body’s ability to absorb nutrients other than calcium.