ajit257 wrote:
The physical structure of the human eye enables it to sense light of wavelengths up to 0.0005 millimeters; infrared radiation, however, is invisible because its wavelength—0.1 millimeters—is too long to be registered by the eye.
(A) infrared radiation, however, is invisible because its wavelength—0.1 millimeters—is too long to be registered by the eye
(B) however, the wavelength of infrared radiation—0.1 millimeters—is too long to be registered by the eye making it invisible
(C) infrared radiation, however, is invisible because its wavelength—0.1 millimeters—is too long for the eye to register it
(D) however, because the wavelength of infrared radiation is 0.1 millimeters, it is too long for the eye to register and thus invisible
(E) however, infrared radiation has a wavelength of 0.1 millimeters that is too long for the eye to register, thus making it invisible
Please can some explain why choice b is not correct ?
Hi! This question is an excellent test of modification, which is heavily tested on the GMAT.
As always, when first evaluating a sentence it's best to ignore the "extra bits" - focus on the subject and verb.
First, we recognize that the semicolon divides two equal sentences; in effect, we can ignore everything that comes before it. So, let's only focus on the underlined portion.
In the original (and, of course, choice (A)), we have:
Quote:
infrared radiation is invisible because its wavelength is too long to be registered by the eye.
Seems like a perfectly sound sentence - it's clear what's invisible (IR), "its" has a single clear antecedent (IR) and no style issues. Lookin' good!
Next up is (B):
Quote:
however, the wavelength ... is too long to be registered by the eye making it invisible.
This one isn't as clear: "it" is supposed to refer to IR, but actually modifies the subject of the sentence, "the wavelength". As noted by our Trojan-loving poster, a prepositional phrase can't be the subject, so even though (B) contains "of infrared radiation" that's not a legal parent noun for "it".
Here's another very useful general rule for the GMAT: ignore prepositional phrases. Such phrases appear all the time and are pretty much always just in there to distract you from the basic sentence structure.
Next we have (C):
Quote:
infrared radiation is invisible because its wavelength is too long for the eye to register it.
More pronoun problems (pronouns are another very commonly tested grammar concept)! "it" at the end of the sentence could refer to either IR or wavelength. When you see an ambiguous pronoun, move on!
(Technically pronouns refer to the closest "legal" preceding parent noun - in this sentence that would be "wavelength" - but for the most part the GMAT abhors pronoun ambiguity.)
How about (D):
Quote:
however, because the wavelength of infrared radiation is 0.1 millimeters, it is too long for the eye to register and thus invisible.
Same issue as (B) - "of infrared radiation" can't be the antecedent for "it".
Finally (E):
Quote:
however, infrared radiation has a wavelength of 0.1 millimeters that is too long for the eye to register, thus making it invisible.
"that" renders this sentence awkward; also, "it" at the end could refer to IR, wavelength or the eye.