Question

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. Oxalic acid has little effect on the body's ability to absorb nutrients other than calcium.

Hint:

To weaken a cause-and-effect argument, look for an answer choice that shows the cause does not lead to the effect. Here, the "cause" is oxalic acid blocking absorption, and the "effect" is the need for other calcium sources. The correct answer provides a way to block the blocker, thus severing the link between the cause and the effect.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
This is a weaken question. The argument concludes that because spinach contains an absorption-blocker (oxalic acid), one must eat \textit{other} calcium-rich foods to get enough calcium. We need to find a statement that breaks this conclusion, suggesting that one can get enough calcium from spinach despite the oxalic acid.
Step 2: Detailed Explanation:
The argument's structure is:

Premise 1: Spinach has calcium.
Premise 2: Spinach also has oxalic acid, which blocks calcium absorption.
Conclusion: Therefore, to get enough calcium, you must eat other sources of calcium.
The unstated assumption is that there's no way to overcome the blocking effect of the oxalic acid \textit{within the context of eating spinach}. To weaken the argument, we need to show that this assumption is false. Let's analyze the options:

(A) This statement provides a way to defeat the effect of oxalic acid. If rice, a common food, negates the oxalic acid, then the body could absorb the calcium from spinach effectively. If this is the case, it may not be necessary to eat \textit{other} calcium-containing foods, as the calcium from the spinach itself would become available. This directly weakens the conclusion.
(B) This states that people who eat spinach also happen to eat other calcium sources. This doesn't weaken the argument's point that they \textit{must} do so to get enough calcium. It simply describes a behavior that is consistent with the argument's conclusion.
(C) This strengthens the argument by confirming that cooking doesn't solve the problem of oxalic acid.
(D) This is irrelevant. The fact that other vegetables also have this problem doesn't change the argument about spinach. If anything, it might broaden the conclusion, but it doesn't weaken the logic regarding spinach.
(E) This is irrelevant. The argument is only about calcium absorption, not other nutrients.
Step 3: Final Answer:
Option (A) most seriously weakens the argument by introducing a mechanism (eating rice) to counteract the oxalic acid, thereby making the calcium in spinach absorbable and undermining the conclusion that other calcium sources are necessary.