Researcher: Soils are adversely affected by road salts used to melt

Question

Researcher: Soils are adversely affected by road salts used to melt ice and snow, particularly along roadsides and salt storage areas. Soil samples were collected from highway medians and in salt storage yards. These samples showed chloride levels 11–160 times the level sufficient to inhibit bacteria growth in soil. The samples also had sodium levels 15–200 times the level sufficient to inhibit bacterial growth in soil. Inhibited bacterial growth in soil greatly inhibits plant growth in that soil.

An agriculture official would like to use the researcher’s results to support the argument that sand, rather than road salts, should be used as a winter road treatment, thereby eliminating the need for salt yards.

Select the additional information that, if true, would most strengthen the official’s case and select the additional information that, if true, would most weaken the official’s case. Make only two selections, one in each column.

bM22 · Accepted Answer

1. A high number of road accidents are attributable to untreated roads in winter.
 Neither of Both  - since it neither weakens the use of sand as a winter road treatment nor strengthens the same.
So irrelevant for us.

2.The cost of removing salts from soil in abandoned salt yards is high.
 Neither of Both  - since it does help in strengthening the claim that use of salt for road treatment need to be replaced, but not specifically strength/weaken the claim by the official regarding the use of sand. So irrelevant for us.

3. High chloride concentrations in drinking water supplies have a negative impact on health. 
 Neither of Both  - since it doesn't help in weakening/strengthening the claim, that the use of sand could either cause this effect, or prevent it.

4. Sand is much less effective than salt at making roads safe to drive in winter conditions.
 Weakens  - Now, this statement says that sand is less effective than salt, directly undermining the claim of the official, implying that sand cannot be a suitable replacement of salt, thus weakening the statement.

5. Runoff from roads is often absorbed by farmland.
 Strengthens  - This statement strengthens the claim of the official, since if sand is used, it would absorb any amount of water that is a runoff from road, as no salt means sufficient amount of bacteria, which in turn implies, plants, which is turn implies any runoff from roads will be absorbed.

So 4th one weakens the claim, and the 5th one strengthens it.

Sajjad1994 · Answer

Official Explanation

There is insufficient information to link drinking water to the agriculture official’s argument, therefore the third option is eliminated.

While the high cost of removing salts from soil in abandoned salt yards could strengthen the official’s case, additional information would need to be presented. For instance, if additional salt yards had been proposed, then switching to sand as a road treatment method could prevent further environmental damage. In the absence of such additional information, the high cost of removing salts from soil in abandoned salt yards does not, in itself, strengthen the official’s case significantly.

The statement that most strengthens the official’s case is that runoff from roads is often absorbed by farmland. Unlike the statement about salt yards, this indicates that maintaining the use of salt as a road treatment presents an immediate consequence for food production—a consequence the agriculture official wants to avoid.

The correct answer is Runoff from roads is often absorbed by farmland.

The high number of road accidents attributable to untreated roads in winter could weaken the case if the official had proposed not treating the roads at all, but as the agriculture official offered sand as an alternative, this option does not affect the official’s proposal. If true, the statement comparing the effectiveness of sand as a road treatment to the effectiveness of salt provides an argument against the use of sand that the official’s argument does not address.

The correct answer is Sand is much less effective than salt at making roads safe to drive in winter conditions.

Apt0810 · Answer

Here Most strengthen: Runoff from roads is often absorbed by farmland,since sand would absorb any amount of water that is runoff from road and if no salt is there then sufficient bacterias are there

Most weaken: Sand is much less
effective than salt at making roads safe to drive in winter conditions.
This statement clearly shows that sand cannot be good alternative when compared with salt

Posted from my mobile device

pranskius · Answer

Could anyone expand on this explanation? "There is insufficient information to link drinking water to the agriculture official’s argument, therefore the third option is eliminated."

In what way is there insufficient information to link drinking water to the agriculture official's argument? Is it because information "chloride levels 11–160 times the level sufficient to inhibit bacteria growth in soil" is not sufficient to infer that these chloride levels are  high ? Therefore, it is impossible to link the choice C which talks about  high  chloride levels?

kaladin123 · Answer

I fell for the same trap answer choice. It's quite cleverly written, actually. 
If one reads carefully, it becomes clear that high chloride levels in drinking water are not relevant to the official's argument, which is about soil.

AnishPassi · Answer

The official's main point is: "sand, rather than road salts, should be used as a winter road treatment, thereby eliminating the need for salt yards"

Why should sand be used instead of road salts as a winter road treatment?

The official must be thinking:
1. Salt is bad for soil, we should not use it.
2. (Sand is a good substitute for winter road treatment), so we should use sand instead.

Statement D: "Sand is much less effective than salt at making roads safe to drive in winter conditions." attacks the assumption the official is making. If sand is significantly inferior, maybe we should not use sand instead of road salts.  D weakens the official's case .

Statement E: "Runoff from roads is often absorbed by farmland."

The passage already mentions that soil samples from highway medians contain very dangerous levels of sodium and chloride. Often what drains away from the road is absorbed by farmland. If winter roads are treated with road salts, the salts probably carry to farmland. Bad for farmland. Bad for plant growth. We should look for a replacement.  E strengthens the official's case.

runoff meaning: "the draining away of water (or substances carried in it) from the surface of an area of land, a building or structure, etc."

playthegame · Answer

Hello  Sajjad1994 , think this question is available in the OG question bank so not sure how come this is tagged GMAT Prep (Focus).

Sajjad1994 · Answer

There might be a chance this question showing up in both of the sources.

mkeshri185 · Answer

How can be E the answer for strengthener? Runoff is never discussed in the passage. We dont know whether it is negative or positive impact? And also how do we know that runoff problem is not solved by salt method and will be solved by sand?

Bunuel · Answer

E strengthens because it supplies the missing link.

If road runoff (water that flows off roads into nearby soil and farmland) is absorbed by farmland, then the salts spread on roads end up in farm soils. The passage already states that high chloride and sodium inhibit soil bacteria and therefore plant growth, so carrying those salts onto farmland is harmful. That creates a direct agriculture impact from road salts, which supports switching away from salt. Sand does not add chloride or sodium, so it avoids this specific contamination even if runoff still occurs. Hence E strengthens the official’s case.

Tucky · Answer

GMATNinja   KarishmaB   MartyMurray 
This one surprised me a bit, and i need help with the ' Most strengthen part.

Inhibited bacterial growth Inhibits plant growth --> choose SAND

I am lil confused about how this strengthen the above argument. 
If the option suggests that SALT is MORE bad. Then it is also possible that SAND is equally if not less damaging in some other way.

If the option suggests that SAND Runoff won't be damaging, then it is  ASSUMING that SAND RUNOFF are RELATIVELY LESS HARMFUL.

Both (A) & (B) seem to eliminate an alternative option/objection, and hence may strengthen the argument.

Am i reading too much? where am i going wrong here?

MartyMurray · Answer

This question isn't very well constructed. So, the credited answer, (E), is not very convincing for the strengthen side.

At the same time, (E) is the best because it at least shows that salt gets absorbed into soil in locations such that salt will be a in position to hurt plants.

Also, we can use some common knowledge in answering GMAT questions, and common knowledge of sand indicates that a little sand would not cause significant problems in similar situations involving farmland.
 
We have to presume that the choice is between salt and sand. So, (A) doesn't strengthen the argument since it only serves to eliminate the choice of using neither.

(B), which is about a cost that is not directly involved in treatment, has no effect at all.

So, we can safely choose (E) as the best choice for the strengthener.

Researcher: Soils are adversely affected by road salts used to melt

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Most strengthen	Most weaken	Statements
		A high number of road accidents are attributable to untreated roads in winter.
		The cost of removing salts from soil in abandoned salt yards is high.
		High chloride concentrations in drinking water supplies have a negative impact on health.
		Sand is much less effective than salt at making roads safe to drive in winter conditions.
		Runoff from roads is often absorbed by farmland.

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Researcher: Soils are adversely affected by road salts used to melt

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