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# A study was designed to establish what effect, if any, the

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Senior Manager
Joined: 12 Mar 2009
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A study was designed to establish what effect, if any, the [#permalink]

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01 Jul 2009, 01:45
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5. A study was designed to establish what effect, if any, the long-term operation of offshore oil rigs had on animal life on the bottom of the sea. The study compared the sea-bottom communities near rigs with those located in control sites several miles from any rig and found no significant differences. The researchers concluded that oil rigs had no adverse effect on sea-bottom animals.
Which one of the following, if true, most seriously weakens the researcher’ conclusion?
(A) Commercially important fish depend on sea-bottom animals for much of their food, so a drop in catches of these fish would be evidence of damage to sea-bottom communities.
(B) The discharge of oil from offshore oil rigs typically occurs at the surface of the water, and currents often carry the oil considerable distances before it settles on the ocean floor.
(C) Contamination of the ocean floor from sewage and industrial effluent does not result in the destruction of all sea-bottom animals but instead reduces species diversity as well as density of animal life.
(D) Only part of any oil discharged into the ocean reaches the ocean floor: some oil evaporates, and some remains in the water as suspended drops
(E) Where the ocean floor consists of soft sediment, contaminating oil persists much longer than where the ocean floor is rocky.

The OA is
[Reveal] Spoiler:
b

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Manager
Joined: 15 May 2009
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Re: A study was designed [#permalink]

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03 Jul 2009, 12:05
vaivish1723 wrote:
5. A study was designed to establish what effect, if any, the long-term operation of offshore oil rigs had on animal life on the bottom of the sea. The study compared the sea-bottom communities near rigs with those located in control sites several miles from any rig and found no significant differences. The researchers concluded that oil rigs had no adverse effect on sea-bottom animals.
Which one of the following, if true, most seriously weakens the researcher’ conclusion?
(A) Commercially important fish depend on sea-bottom animals for much of their food, so a drop in catches of these fish would be evidence of damage to sea-bottom communities.
(B) The discharge of oil from offshore oil rigs typically occurs at the surface of the water, and currents often carry the oil considerable distances before it settles on the ocean floor.
(C) Contamination of the ocean floor from sewage and industrial effluent does not result in the destruction of all sea-bottom animals but instead reduces species diversity as well as density of animal life.
(D) Only part of any oil discharged into the ocean reaches the ocean floor: some oil evaporates, and some remains in the water as suspended drops
(E) Where the ocean floor consists of soft sediment, contaminating oil persists much longer than where the ocean floor is rocky.

(A) Out of scope, there is nothing here to suggest that the damage mentioned was a result of oil rigs.
(C) Out of scope, this does not discuss oil rigs, but other source of pollution.
(D) Irrelevant, does not discuss damage to the sea bottom organisms FROM OIL RIGS.
(E) Irrelevant for the same reason as above.

(B) The only reasonable choice. The original info suggests that even though the waters near oil rigs may not be polluted, other sea bottom areas are damaged. This directly undermines the conclusion that oil rigs have "NO" adverse effects on sea-bottom animals.

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Manager
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Re: A study was designed [#permalink]

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21 Jul 2009, 02:52
(A) Commercially important fish depend on sea-bottom animals for much of their food, so a drop in catches of these fish would be evidence of damage to sea-bottom communities.
- Irrelevant, refuted in the passage
(B) The discharge of oil from offshore oil rigs typically occurs at the surface of the water, and currents often carry the oil considerable distances before it settles on the ocean floor.
- Weaken
(C) Contamination of the ocean floor from sewage and industrial effluent does not result in the destruction of all sea-bottom animals but instead reduces species diversity as well as density of animal life.
- Strengthen
(D) Only part of any oil discharged into the ocean reaches the ocean floor: some oil evaporates, and some remains in the water as suspended drops
- Neither
(E) Where the ocean floor consists of soft sediment, contaminating oil persists much longer than where the ocean floor is rocky.
- Irrelevant

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Director
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Re: A study was designed [#permalink]

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21 Jul 2009, 02:57
Agree with b. Only choice makes sense.
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Re: A study was designed   [#permalink] 21 Jul 2009, 02:57
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