5) In 1914 a total of 469,000 cars and trucks were produced in the United States, but in 1929 almost twice the numbers of trucks alone came off the assembly lines.
A) the numbers of trucks 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
Meaning: The statement states a comparison. In 1914, US produced cars + trucks = 469,000. But in 1929, it produced twice that number of trucks alone.
Choice Analysis: A) "the numbers of..." is a wrong idiom. The correct idiom is "the number of...".
B) Correct. "twice that number" clearly refers to the figure 469,000. "alone" is correct for "trucks" because the sentence has two objects: cars and trucks. Trucks is one object in the sentence which is written in plural. In 1929, the US produced twice that number of trucks alone, no cars.
C) Although, "trucks" is plural, in this sentence it has been used as collective noun to mean a single object. Therefore, plural themselves shall not be used here.
D) Although, "trucks" is plural, in this sentence it has been used as collective noun to mean a single object. Therefore, plural themselves shall not be used here.
E) Although, "trucks" is plural, in this sentence it has been used as collective noun to mean a single object. Therefore, plural themselves shall not be used here.
So, I go for B.