PrepTest 117, Section 3, Question 18
Until 1985 all commercial airlines completely replenished the(52 more words not shown)
Which one of the following(8 more words not shown)
- AIn 1985 there(12 more words not shown)
- BPeople who fly(16 more words not shown)
- CLow levels of(13 more words not shown)
- DIn 1980 the(23 more words not shown)
- EIn 1980 the(24 more words not shown)
Reading the argument
The air is being replaced less often. The passage tells us what that change does; it doesn't tell us why the airlines made it.
In the earlier period, cabin air was fully replenished every 30 minutes. In the later period described here, it is replenished every hour. Maybe the airlines wanted to cut costs, or maybe they thought the earlier rate was unnecessary. Those are only guesses about the reason. We don't need them to follow the stated relationship.
Less frequent replenishment means higher carbon dioxide levels and conditions that make airborne illnesses easier to spread. So the direction of the comparison is clear: the later schedule produces the higher carbon dioxide level on a similar flight. We're comparing the periods in the passage, not checking present-day airline practices.
What we’re looking for
The question asks what is most strongly supported. Keep the answer close to that change and its stated effects. I'll look for the connection between the longer interval, the higher carbon dioxide level, and the easier spread of illness, without adding a guess about why the schedule changed.
Working the answers
- A
A change in airline practice doesn't establish a change in regulations. Perhaps the old rules already allowed the slower replenishment rate and airlines chose to adopt it. The passage tells us what the airlines did, not what the rules required before or after 1985.
- B
Easier spread under one set of cabin conditions isn't the same as a greater overall chance that a traveler contracts an illness. Other factors could have changed. For example, changes in vaccination or mask use could affect infection risk independently of air replenishment. Those are possible factors, not facts we're adding about these flights. B goes beyond the particular effect the passage gives us.
- C
Easier to spread doesn't mean impossible to spread under the alternative conditions. A lower carbon dioxide level could accompany a reduced opportunity for transmission while some transmission still occurred. The passage never establishes a zero-risk level.
- D
We know the 1980 replenishment rate was faster. We aren't told it completely protected passengers from the effects of carbon dioxide buildup. A better condition need not be a fully protective condition. D adds a safety threshold the passage never supplies.
- ECorrect
In 1980, a commercial flight used the 30-minute replenishment schedule. In the later period, a similar flight uses the one-hour schedule. The passage says less frequent replenishment produces higher carbon dioxide levels, so the earlier two-hour flight had the lower level. E applies that stated comparison without needing a new fact about regulations, immunity, or a safe threshold.
More Must Be True questions
Learn the LSAT our way
Our platform drills Must Be True questions at your level and adjusts as you improve.