I have a doubt regarding parallelism. Consider the below sentences:
Sentence#1
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Visitors to the park have often looked up into the leafy canopy and saw monkeys sleeping on the branches, whose arms and legs hang like socks on
a clothesline.
(A) saw monkeys sleeping on the branches, whose arms and legs hang
(B) saw monkeys sleeping on the branches, whose arms and legs were hanging
(C) saw monkeys sleeping on the branches, with arms and legs hanging
(D) seen monkeys sleeping on the branches, with arms and legs hanging
(E) seen monkeys sleeping on the branches, whose arms and legs have hung
OA is (D).
I chose (C). Explanation says (C) is incorrect because "have looked" is not parallel to "saw" ... they are in different tenses.
Sentence#2
========
But consider the below sentence, which is officially correct.
XYZ, vortices of gas associated with strong magnetic activity, are visible as dark spots on the surface of the Sun but have never been sighted on the Sun’s poles or equator.
Applying the explanation of sentence#1, "are visible" is not parallel to "have ... sighted". How come sentence#2 is correct?
Could Ron or Stacy please throw some light on this?
Thanks,
Saunak