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

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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