单选题 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.

【正确答案】 A

【答案解析】[解析] 本题根据Spinach中的Oxalic acid能阻碍人体对钙的吸收，做出了其他含钙的物质应该被食用的结论。要对本题的结论构成反对，就要从Oxalic acid入手。既然Oxalic acid能阻碍人体对钙的吸收，那么有没有其他的物质能抑制Oxalic acid的这种对人体吸收钙的不良影响?(A)选项指出大米可以与Oxalic acid中和，对结论成立的前提进行了削弱，从而对结论进行了削弱。因此(A)为正确答案。(B)、(C)、(D)、(E)都不能对本题结论成立的前提构成反对。