DebbieChats, Can you remove the off topic and other doubts you have from the answer options and ask in the spoiler?

A detailed explanation, please?
IMO B is correct as "unlike other birds" is used and secondly "unique abilities" is mentioned, both of which signify that only hummingbirds perform can these activities.
Option A refutes the argument by using "some". "None of the other" would have been an equally valid choice?

Please share your thoughts.

Hi,
Could an expert provide his opinion about this one... I chose B, because I focused on the phrases"unlike any other bird and" and "unique ability to perform..." so I I thought A is wrong, because by some we assume that there is a number of birds that can actually do those things, thus eventually contradicts with the stem right?

Humming birds have the unique ability to perform "hovering". That definitely means there are some birds who can not hover.
Option A follows and is the answer.
VeritasKarishma /
GMATNinja right ?

Posted from my mobile device

Great question ajmekal, and here's the thing to be aware of regarding the use of the word "some."

"Some" can represent any plural number.

If it is true that very few people like swimming, then "some people" like swimming.

If it is true that most people like swimming, then "some people" like swimming.

If it is true that all people like swimming, then still, "some people" like swimming.

At the same time, people don't necessarily think of "some" as representing "all" or "most." "Some" has multiple connotations, and can be perceived as representing a relatively small fractional proportion of a total.

Because "some" has these connotations, it is used in GMAT Critical Reasoning questions to obscure the meanings of choices, and to make incorrect answers seem correct and correct answers seem incorrect.

In this case, the idea is that all birds other than the hummingbird cannot hover. Clearly, if all birds other than the hummingbird cannot hover, then it is true that some birds cannot hover.

So, if you agree that the passage indicates that only hummingbirds can hover, which inference is actually somewhat debatable, then (A) is correct.

(Whether choice (A) is actually correct is debatable, as the passage could be interpreted as saying that only the hummingbird can perform all of the "several feats of acrobatic flight," leaving open the possibility that other birds can perform one or more of those feats, just not all of these feats.)
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Yes, you are right. It certainly seems that this is what the test maker wanted you to infer. But I certainly feel an ambiguity in the way it is written.

Is the ability to perform several feats unique (other birds can perform one or two of them but not several)? Or is the ability to perform each of those feats unique (no other bird can hover, no other bird can fly backwards etc)?
Though if all birds could hover, one would not be able to say that it is a "feat of acrobatic flight". It would be just a part of flying.
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