Sentence Correction

The Dancing Doll line sold slightly more than $3.5 million worth of toys last year, 40% more than the Teeny Trucks line and nearly 3 times as much as Basic Blocks line's sales.

A)....
B) the Teeny trucks did and nearly 3 times what the Basic Blocks' sales were
C) the Teeny trucks line sold and nearly 3 times as much as basic Blocks' sales
D) the Teeny trucks line and nearly 3 times more than Basic blocks' sales.
E) the Teeny trucks line and nearly 3 times more than the Basic Blocks line.

Obviously here comparison is being made between 3 toy companies but what exactly is compared? Is it the amount or the manufacturers themselves? I chose C but the answer given was E

Tricky one.

The sentence actually compares dancing doll line, teeny truck line and basic block line. We can take a cue from 'sales' in C (others are 'sold')

Comparison is being done on the brands or the manufacturers (i.e. Dancing Doll line, Teeny trucks line and basic blocks line), the basis of comparison is the amount sold.
In the original sentence, the word sales at the end sticks out like a sore thumb. Try and break down the sentence like:

Dancing doll line sold slightly more than $3.5 million worth of toys.
Dancing doll line sold 40% more than Teeny trucks line.
Dancing doll line sold nearly 3 times as much as Building block line's sales.

Here we can see that the comparison is being made between amount sold by Dancing Doll line (the brand) and Basic Blocks line's sales, which is illogical as it implies Building Block line's sales was sold.
correct statement would be the one comparing the lines:
Dancing doll line sold nearly 3 times more than Building block line.

EDIT:
Forgot to put it in words, my vote is for E.

what is the source of the question

I got B

Eliminated A, B, C because more than is used to compare number of toys sold between Dancing doll and Teeny Toys line, so the same expression should be used to compare Teeny Toys line and Basic Block line.

40% more than the Teeny Toys line and nearly 3 times more than Basic Block line's sales

Sales is not being compared, but the number of toys sold and hence D is wrong.

E is correct

Here is a small shortcut:

Always, or in most cases, rule out possessives in GMAT.