LSAT 135 | Section 4 | Logical Reasoning: Q6

LR Question 6 Explanation

QUESTION TEXT: The calm, shallow waters of coastal estuaries are…

QUESTION TYPE: Must Be True

FACTS:

1. Sewage can fill estuaries with nutrients.
2. This causes algae.
3. This causes microorganisms.
4. This kills most of the fish.

ANALYSIS: It sounds like sewage can indirectly kill fish.

Sewage ➞ Algae ➞ Microorganisms ➞ Most fish die

___________

1. The passage mentioned that fish die from microorganisms. It didn’t mention fish dying directly from sewage.
2. We know that the microorganisms reproduce more quickly when algae is present. We don’t know whether they reproduce more quickly than other organisms. This is the wrong comparison.
3. It’s quite possible that sewage poisons fish directly. The fact that sewage has an indirect effect doesn’t prevent it from having a direct effect. 
4. Sewage is a sufficient condition for algae, but it’s not a necessary condition. There may be other things that cause algae to spread.
5. CORRECT. This is a straightforward combination of the facts from the stimulus. You should read all the answers before thinking too hard about any of them: this answer is fairly obviously correct, but the LSAC placed it at the end to make you waste time.