Sentence Correction

Q14:
In 1914 a total of 469,000 cars and trucks were produced in the United States, but in 1929 almost twice the numbers of tucks alone came off the assembly lines.
A. the numbers of tucks alone
B. that number of trucks alone
C. the number of trucks by themselves
D. as many trucks themselves
E. as many trucks by themselves

To my view, B should be the answer.

OA please

OA is B
Would you please explain why that is necessary here

Saurabh ,
On reading the sentence carefully we find that ... the number being referred to is 469,000. Hence we use "that".

HTH

A. the numbers of tucks alone : numbers > number
B. that number of trucks alone
C. the number of trucks by themselves: by themselves > wordy and not idiomatic
D. as many trucks themselves: as many as > as omitted
E. as many trucks by themselves: as many as > as omitted

I would go for B