few pointers:
-> quietest is a superlative and needs a noun or a preposition tagged to it.
-> the subtle change implied here is parallelism error.
-> Also observe the sentence starts with 'because'- dependent clause. so we cannot have a conjunction 'and' connecting a dependent clause with an independent clause.
-> keeping in mind these pointers, parallelism between quietest and the most elusive of submarine needs to exist.

(A) and it is therefore the most elusive submarine, it is being increasingly viewed [ dependent and independent clauses are connected.]

(B) it is therefore the most elusive of submarines, and it has increased the view [ship has increased the view? how can ship increase some view?]

(C) and therefore the most elusive submarine, it is being increasingly viewed [correct! quietest and elusive are parallel. this is one of the questions where 'being' is correct! tats why i tell, never eliminate 'being' just by looking at it]

(D) and therefore it is the most elusive of submarines, there is an increasing view [ again independent and dependent clauses are connected. wrong!]

(E) therefore being the most elusive of submarines, it is increasingly viewed [ conjunction 'and' is required to maintain parallelism]

hope this helps!

thephoenix wrote: but i thought being is always wrong in GMAT, can anybody help

Answers choices with "Being" are almost always wrong. However, you should never rule out an answer choice on the basis of "being" alone. Being only comes into play if you are stuck between two answer choices ... in that case, check if being is redundant and can be avoided.

Hope this helps.