Adding ethanol to the gasoline used in cars reduces exhaust emissions

Let's take a second look at the passage:


OK, so here's what we've got:

• Adding ethanol to gas reduces exhaust emissions.
• Adding ethanol to gas slightly increases evaporative emissions.
• Evaporative emissions are a major component of smog, which is found in many large cities in hot summer months.
• But evaporative emissions pose less of a pollution problem than exhaust emissions, except in hot weather.
• Therefore, if air pollution were the only consideration, one would conclude that ______________________________.

The author tells us that evaporative emissions contribute to a kind of air pollution (smog), BUT this mainly happens in large cities and during hot summer months. When the weather is not hot, evaporative emissions pose less of a pollution problem than exhaust emissions.


Our job is the fill in the blank, based on what the author has already said. Well, if air pollution is the only thing that we care about, then we know the author prefers evaporative emissions over exhaust emissions, except in hot weather (especially in hot weather within big cities). So just by reading the text, we can infer the author will prefer adding ethanol to gas except in hot weather (especially in hot weather within big cities).

Addressing your concern about cold weather, recall that the author writes:

"...except in hot weather, evaporative emissions pose less of a pollution problem than exhaust emissions."

Here, the author is logically telling us:

Evaporative emissions pose less of a pollution problem than exhaust emissions in all weather except hot weather.

So we do know what the author thinks about the impact of ethanol during winter months (which it's safe to assume are cold, or at the very least, not hot).

Now let's eliminate anything that's not consistent with the author's point of view:

This is the opposite of what the author would like! We know that ethanol leads to more smog in large cities during hot summer months. The author would not recommend adding ethanol only to gasoline intended for use in these cities without some kind of targeted timing for when the ethanol is added. But this choice doesn't give us that kind of detail, so we eliminate (A).


This is also the opposite of what the author has written so far. The author says that except in hot weather, evaporative emissions pose less of a pollution threat than exhaustive emissions. Eliminate (B).


This looks good! When considering pollution, the author believes that the disadvantages of adding ethanol to gas match or outweigh the advantages in hot weather. Choice (C) states that the advantages of adding ethanol to gas (lower exhaust emissions) likely outweigh the disadvantages (slightly higher evaporative emissions), at least in cold weather (when there's less risk of the evaporative emissions contributing to smog). Let's keep (C) around.


The author has spent the entire passage discussing how we can use ethanol to reduce exhaust emissions, in the context of a "pollution problem." Given that pollution is the only consideration for our answer, this would contradict, not complete, everything the author has already written. Eliminate (D).


Like (A), this choice says the opposite of what the author has stated. Adding ethanol to gasoline in the cities in hot weather would contribute to smog, which is a form of air pollution. The end result would be lower air quality, not higher air quality. So eliminate (E).

(C) is the best choice available. I hope this helped clear up the air around this question! I also hope my dad jokes don't exhaust anyone today!

(Wow, those jokes were some of my worst ever. Can I fire myself?)