LSAT Explanation PT 24, S3, Q5: Bacteria from food can survive for

LSAT Question Stem

Which one of the following is an assumption on which the argument depends? 

Logical Reasoning Question Type

This is a Necessary Assumption question. 

Correct Answer

The correct answer to this question is D. 

LSAT Question Complete Explanation

Let's first analyze the argument in the passage. The argument states that bacteria from food can survive on plastic cutting boards for several days, but they can penetrate wooden cutting boards almost immediately, leaving the surface free of contamination. Based on this, the conclusion is that wooden cutting boards do not need to be washed to prevent contamination; wiping them off is sufficient.

The structure of the argument is as follows:

Premise 1: Bacteria can survive on plastic cutting boards for several days.

Premise 2: Bacteria penetrate wooden cutting boards almost immediately, leaving the surface free of contamination.

Conclusion: Wooden cutting boards do not need to be washed to prevent contamination.

Now let's come up with an "Evaluate" question for this argument: "Do bacteria that penetrate wooden cutting boards reemerge on the surface after the cutting boards have been used?"

The question type for this problem is Necessary Assumption, which asks us to identify an assumption on which the argument depends. Let's go through each answer choice:

a) Washing plastic cutting boards does not remove all bacteria from the surface.

This answer choice is not a necessary assumption for the argument because the argument focuses on wooden cutting boards, not plastic ones. The argument would still hold even if washing plastic cutting boards removes all bacteria from the surface.

b) Prevention of bacterial contamination is the only respect in which wooden cutting boards are superior to plastic cutting boards.

This answer choice is not necessary for the argument because the argument is only concerned with preventing bacterial contamination, not comparing wooden and plastic cutting boards in other aspects.

c) Food that is not already contaminated with bacteria can be contaminated only by being cut on contaminated cutting boards.

This answer choice is not necessary for the argument because it doesn't address the main point of the argument, which is about the effectiveness of wiping wooden cutting boards to prevent contamination.

d) Bacteria that penetrate into wooden cutting boards do not reemerge on the surface after the cutting boards have been used.

This answer choice is the correct one because it is a necessary assumption for the argument. If bacteria were to reemerge on the surface of wooden cutting boards after they have been used, then wiping them off would not be sufficient to prevent contamination. The argument depends on the assumption that the surface of wooden cutting boards remains bacteria-free after use.

e) Washing wooden cutting boards kills bacteria below the surface of the cutting boards.

This answer choice is not necessary for the argument because the argument is about whether wiping wooden cutting boards is sufficient to prevent contamination, not whether washing them kills bacteria below the surface.

In conclusion, the correct answer is D because the argument depends on the assumption that bacteria do not reemerge on the surface of wooden cutting boards after they have been used. This ensures that wiping the surface is sufficient to prevent contamination.