Sentence Correction

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 dark spots 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

OAA

Can I eliminate option C because correct idiom is appear to be, if no then please explain the reason to eliminate this option.

Thanks,

Kavin

One definition of to appear is to seem.
When appear serves to convey this meaning, appear as is unidiomatic.
INCORRECT:
John appears as the best player on the team.
CORRECT:
John appears to be the best player on the team.
Conveyed meaning:
John SEEMS to be the best player on the team.

Another definition of to appear is to come into view.
When appear serves to convey this meaning, appear as is a viable construction.
CORRECT:
Sunspots appear as dark spots.
Conveyed meaning:
Sunspots COME INTO VIEW in the form of dark spots.

Thus, D cannot be eliminated because of the usage of appear as.
I posted an explanation for this SC here:
https://www.beatthegmat.com/question-on- ... 41410.html