Tungsten and Its Chemical Properties

u need a contrast and so the choice C and E are left !!
E is more parallel than C
tungsten is used ......yet is so adaptable

This question was rather difficult for me. I got the answer by the process of elemination:

A -> incorrect, because "so adaptable" seems to refer to "filaments"
B -> incorrect, same reason
C -> incorrect, again same reason
D -> incorrect, the part after "and" either must be parallel with "filaments" (so a noun) or a full sentence. Both is ot the case
E -> correct, because apparently you can omit the subject "tungsten" in the second part after "yet"

my question would be what the rule is for omiting parts of sentences.

srcc25anu wrote:Having one of the highest melting points of all the chemical elements, tungsten is used in temperature-dependent products such as light bulb filaments so adaptable that it is also used to make wedding bands.

A. filaments so adaptable
B. filaments being so adaptable
C. filaments, yet being so adaptable
D. filaments, and so adaptable
E. filaments yet is so adaptable

OA: E

A. LIGHT BULB FILAMENTS so adaptable that IT is also used to make wedding bands
B. LIGHT BULB FILAMENTS being so adaptable that IT is also used to make wedding bands
These answer choices seem to imply that LIGHT BULB FILAMENTS are so adaptable that IT (tungsten) is also used to make wedding bands -- a nonsensical meaning.
The intended meaning is that TUNGSTEN is so adaptable that it is also used to make wedding bands.
Eliminate A and B.

C: tungsten IS USED in temperature-dependent products such as light bulb filaments, yet BEING SO ADAPTABLE
D: tungsten IS USED in temperature-dependent products such as light bulb filaments, and SO ADAPTABLE
Conjunctions such as yet and and must connect PARALLEL FORMS.
In C, yet cannot serve to connect IS USED (verb) with BEING SO ADAPTABLE (adjective phrase).
In D, and cannot serve to connect IS USED (verb) with SO ADAPTABLE (adjective phrase).
Eliminate C and D.

The correct answer is E.

In the OA, yet serves to connect two VERBS: tungsten IS USED...yet IS.
Here, it's clear that tungsten is serving as the subject for both verbs (is used and is), so there is no need to repeat the subject.