LSAT 135 | Section 2 | Logical Reasoning: Q23

LR Question 23 Explanation

QUESTION TEXT: Certain bacteria that produce hydrogen sulfide …

QUESTION TYPE: Most Strongly Supported

FACTS:

• Certain bacteria produce hydrogen sulfide.
• The hydrogen sulfide removes oxygen that would otherwise kill the bacteria.
• It also kills nearby organisms that the bacteria can eat.
• Because of this, a dense colony can keep itself alive indefinitely.

ANALYSIS: The key is the final sentence: As a result, a dense colony …

Everything before that explains why.

The chain is: produce hydrogen sulfide → removes oxygen → protects bacteria → also kills nearby organisms → dead organisms become food.

So a dense colony creates an environment that both:

• protects it from oxygen, and
• provides a food source

For MSS questions, be careful not to strengthen the facts. The correct answer should stay close to what the stimulus actually says.

___________

1. CORRECT. This is essentially a paraphrase of the last sentence. If the colony can thrive indefinitely because the hydrogen sulfide keeps removing oxygen and providing food, then it must continue producing enough hydrogen sulfide to do those jobs.
2. The stimulus gives two separate effects: it reacts with oxygen AND it kills other organisms. It never says the second happens because of the first.
3. Too strong. The stimulus only says the hydrogen sulfide tends to kill other organisms, thereby providing a food source. It never says most organisms become food.
4. “Only” is way too strong. The stimulus never says these are the only conditions under which the bacteria can survive. It also says hydrogen sulfide removes oxygen, not necessarily all oxygen.
5. The stimulus is about a particular kind of bacteria and specifically says a dense colony creates this environment. This incorrectly generalizes to any colony of any bacteria that produce hydrogen sulfide.