Question

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.

• A. are visible as dark spots on the surface of the Sun but have never been sighted on
• B. are visible as dark spots that never have been sighted on the surface of the Sun
• C. appear on the surface of the Sun as darkspots although never sighted at
• D. appear as dark spots on the surface of the Sun, although never having been sighted at
• E. appear as dark spots on the Sun's surface, which have never been sighted on

Answer 1

The correct option is A are visible as dark spots on the surface of the Sun but have never been sighted on

The sentence has a parallel structure as it has a list/ series of items/ actions separated by commas. The correct parallel structure in the original sentence emphasizes the difference between where sunspots are found (are visible as dark spots on the surface of the sun) and where they are not (have never been sighted on the sun's pole or equator). In option B, the change from 'have never been...' to 'that never have been...of the sun' distorts the meaning of the sentence. 'Although' typically introduces a subordinate clause (a clause introduced by a conjunction that depends on a main clause), which has a subject and a verb, but here, in option C, there is no subject and 'sighted' is not a complete verb. Option D has the same issue as C but instead of 'sighted', here, 'having been sighted' is not a complete verb phrase. In option E, the relative pronoun 'which' illogically refers to 'surface' when it actually should have made a reference to either 'sunspots' or 'dark spots'. Only option A makes the correct contrast that between where the spots are found and where they aren't. It is the only option that makes logical and grammatical sense.