Sunspots, vortices of gas associated with strong electromagnetic activity, are visible as dark spots on the surface of the Sun but have never been sighted on the Sun’s poles or equator.
(This question is from Official Guide. Therefore, because of copyrights, the complete question cannot be copied here. The question can be accessed at GMAT Club)
- Sunspots, (Subject)
- vortices of gas associated with strong electromagnetic activity, (Noun + Noun modifier, or Absolute Phrase, modifying the subject)
- are visible as dark spots on the surface of the Sun (First Verb – “are”)
- but have never been sighted on the Sun’s poles or equator. (Second Verb – “have never been sighted” — ‘never’ is actually an adverb)
The sentence says that although sunspots are visible as dark spots on the surface of the Sun, they have never been seen on the Sun’s poles or equator.
The sentence has no grammatical or logical errors. Both the verbs “are” and “have been” agree with the subject Sunspots. The contrast between the two verbs is communicated correctly with the use of “but”.
(B) Incorrect. For the following reasons:
- This option when inserted into the sentence will read at the end “on the surface of the Sun the Sun’s poles or equator”, a construction that doesn’t make sense.
- The position of “never” before “have” isn’t appropriate.
(C) Incorrect. Even though the use “although + verb-ed modifier” is not incorrect, as explained in this article, this option is not as clear as option A because of the end-of-clause position of “although never sighted”.
(D) Incorrect. “having verb-ed” indicates an earlier event in a sequence of events. Clearly, the sentence didn’t intend to present the two events in a sequence in which one event was completed before the other. Also, the position of “never” before “having” is inappropriate.
(E) Incorrect. This option changes the meaning of the original sentence. This option says that the dark spots have never been sighted on Sun’s poles or equator. The original sentence said that sunspots have not been sighted on Sun’s poles or equator.