According to the country’s largest television manufacturer, increase in sales of its LED televisions, which have excellent picture quality and
they also consume less power, accounts for most of the 120% increase in revenues that the company experienced last year, the rest of it coming from sales of LCD and plasma televisions.
(A) they also consume less power, accounts for most of the 120% increase in revenues that the company experienced last year, the rest of it coming-> After "and" we have "they also" It is not parallel to " which have ..."
(B) they also consume less power, account for most of the 120% increase in revenues that the company experienced last year, the rest of which came-> After "and" we have "they also" It is not parallel to " which have ..."
(C) which also consumes less power, account for most of the 120% increase in revenues that the company experienced last year; the rest of it came-> Okay, now Parallelism error is corrected. There is Subject verb agreement, "LED televisions" (plural)...with "consumes" (singular).
(D) which also consume less power, accounts for most of the 120% increase in revenues that the company experienced last year, the rest of which came-> Okay, now Parallelism error and Subject verb agreement are corrected. Now, why we are saying "the rest of which" It refers to company experienced last year. It doesn't make sense.
(E) which also consume less power, accounts for most of the 120% increase in revenues that the company experienced last year, the rest of the increase coming-> Okay, now Parallelism error and Subject verb agreement are corrected. Now, "the rest of the increase" refers to revenue. which makes sense.
So, I think E.