Because the enemy's new ship is the quietest and it is therefore the

OFFICIAL EXPLANATION

bravoseries , welcome to GMAT Club!

Prateekj05 and Darshi04 (belated welcome!), I very nearly did not craft an OE because your answers are superb.

I decided to emphasize aspects that neither of you covered or that one or both of you covered somewhat cryptically.

This question belongs in the category, When to Look for the Errors that are the Easiest to Spot.

But which errors are easier to spot, an independent clause ("it is") that does not belong
and ruins a logical connection embedded in another logical connection, or
misuse of the word "view" and a "being" that is clearly out of place?

I think that the second issues are easier.

• Errors in the second part of the sentence

• B incorrectly and illogically uses "it has increased the view" by the military as a threat to security.
A submarine cannot increase a view [OF WHAT?] BY the military
The enemy ship does not make the view more numerous or more expansive.
Further, view by is not correctly used.
"increased the view by" ruins the correct logic of "a something IS viewed BY someone AS XYZ."
-- Eliminate B

• D illogically uses there is an increasing view by.
Because the new ship is the most elusive of submarines, there is an increasing view [OF WHAT] by the military as a threat to security.
1) A view can be held by the military. A view can be described as "among the military."
But a view BY the military is nonsensical.
2) the referent is missing: there is an increasing view IN or AMONG the military OF the enemy ship as a threat to security.
A view implies "a view OF something" as a threat. The something is missing.
-- Eliminate D

• E lacks a logical connector and unnecessarily inserts the word "being"
Because the enemy's new ship is the quietest therefore being the most elusive of submarines. . .
E is missing a conjunction (the quietest and therefore the most elusive)
E's use of being is extraneous and incorrect.
X is the Y and [is] therefore the Z construction is violated.
E incorrectly states X is the Y therefore being the Z
-- Eliminate E

The harder question: A or C?
Exactly one pair of words distinguishes A from C: it is

A) Because the enemy's new ship is the quietest and it is therefore the most elusive submarine, it is being increasingly viewed by the military as a threat to security.

C) Because the enemy's new ship is the quietest and therefore the most elusive submarine, it is being increasingly viewed by the military as a threat to security.

The word "quietest" describes something.
If we saw "quieter," for example, we would look for a mention of two submarines.

If we use a comparative word (quieter, quietest) with a thing, that thing is being compared to another thing or things. We cannot compare a thing to nothing. The other item(s) in the comparison have to be mentioned correctly.

When we see quietest we know we need to find at least a reference to
a group of somethings to which "quietest" is directly attached.

The challenge is that we have a singular noun, submarine.

Parallel and condensed construction
-- The enemy's ship is the quietest [the quietest what?]
-- The enemy's ship is the quietest [vessel of all the enemy's vessels/submarines].
-- The enemy's ship is the quietest [submarine of all the enemy's submarines] and therefore the most elusive submarine [of all the enemy's submarines].
Now we have parallel construction, which then is condensed:
-- The enemy's ship is the quietest and therefore the most elusive submarine.

That construction is in correct answer C.

• Option A incorrectly inserts "it is."
The "it is" interrupts the connection between "quietest" and "submarine."

There is no mention of submarines right after "quietest."
"Quietest" gets connected to its object [the quietest WHAT?] only through the phrase "and therefore the most elusive submarine."
. . . ship is the quietest [and therefore the most elusive] submarine

Option A creates a "quietest" something, but the subsequent IT is severs the tie between quietest and submarine
"Because the enemy's new ship is the quietest [the quietest WHAT?] and it is therefore the most elusive submarine. . ."
"The quietest" cannot "hop over" a pronoun and another verb in order to connect to the most elusive.
Wrong: "The enemy's ship is the quietest [WHAT? ship?] and therefore it is the most elusive submarine"
--Eliminate A

• Meaning and Embedded Logic:
Level 1 logic:
The enemy's new ship is the quietest submarine of all the enemy's submarines and therefore the most elusive submarine of all the enemy's submarines.
Level 2 logic:
Because this submarine is so elusive, the military increasingly views it as a threat to security.

1) Q, therefore E
(Because Q, E)
Q => E
2) Because E, T
(E, therefore T)
E => T

We have one logical relationship embedded in another:
(1) The new ship is the quietest submarine [of all the enemy's submarines]; therefore, it is the most elusive submarine [of all the enemy's submarines]
X is the the quietest of all submarines; therefore X is the most elusive of all submarines

(2) Because the submarine is the most elusive submarine [of all the enemy's submarines], it is viewed by the military as a threat.
X is the enemy's most elusive submarine; therefore X is viewed as a military threat

• Therefore is not redundant.

-- The embedded logic makes "therefore" necessary to connect quietest to most elusive
in a way that is separate from the logical connector [Because] of the larger sentence in which quietest/elusive is embedded.
-- The larger sentence contains another, different connector—because
Because X is the most Y, X is being increasingly viewed by the military as a threat to security.

Darshi04 and Prateekj05 - bravo. Impressive. Kudos to both.