Car owners who inflate their tires properly can substantially boost th

A) Car owners who inflate their tires properly can substantially boost their vehicles’ fuel efficiency, since the increase in car-road friction can waste up to five percent of car fuel by underinflation.

the ending "by underinflation" is wrongly placed, should be placed after "in car-road friction"

(B) Because the underinflation of tires can waste up to five percent of a car’s fuel by increasing car-road friction, car owners can substantially boost their vehicles’ fuel efficiency by properly inflating the tires.

Correct

(C) Their vehicles’ fuel efficiency is substantially boosted by car owners through the proper inflation of tires that, when underinflated, can waste up to five percent of car fuel by an increase in car-road friction.


"their vehicles's fuel" - awkward beginning

(D) The proper inflation of tires by car owners, due to the fact that underinflation can waste up to five percent of a car’s fuel by the increase of car-road friction, can substantially boost their fuel efficiency.


too wordy

(E) Because up to five percent of a car’s fuel are wasted through the increases in car-road friction when the tires are underinflated, car owners properly inflating tires can substantially boost their fuel efficiency.


"car's fuel are" is incorrect, should be "is"; "car owners properly inflating tires" is awkward

B...

(A) Car owners who inflate their tires properly can substantially boost their vehicles’ fuel efficiency, since the increase in car-road friction can waste up to five percent of car fuel by underinflation. doesnt really make sense.
(B) Because the underinflation of tires can waste up to five percent of a car’s fuel by increasing car-road friction, car owners can substantially boost their vehicles’ fuel efficiency by properly inflating the tires.
(C) Their vehicles’ fuel efficiency is substantially boosted by car owners through the proper inflation of tires that, when underinflated, can waste up to five percent of car fuel by an increase in car-road friction. their is not clear.
(D) The proper inflation of tires by car owners, due to the fact that underinflation can waste up to five percent of a car’s fuel by the increase of car-road friction, can substantially boost their fuel efficiency. by the increase of...dont think this is the correct usage...
(E) Because up to five percent of a car’s fuel are wasted through the increases in car-road friction when the tires are underinflated, car owners who properly inflating tires can substantially boost their fuel efficiency.

A has ambiguity:

SINCE is correct usage here. It is a modifier problem in the introductory part:
Car owners who inflate their tires - means car owners have the tyres

In B, we have causual idiomatic relationship, X happened..., Y happened.

(A) Car owners who inflate their tires properly can substantially boost their vehicles’ fuel efficiency, since the increase in car-road friction can waste up to five percent of car fuel by underinflation.

Answer: This is good but makes it unclear that under-inflation can result in increased friction. As written it reads that results from owners who do inflate their tires.

(B) Because the underinflation of tires can waste up to five percent of a car’s fuel by increasing car-road friction, car owners can substantially boost their vehicles’ fuel efficiency by properly inflating the tires.

Answer: Good, (B) is the correct answer.

(C) Their vehicles’ fuel efficiency is substantially boosted by car owners through the proper inflation of tires that, when underinflated, can waste up to five percent of car fuel by an increase in car-road friction.

Answer: Just read it - doesn't even make sense.

(D) The proper inflation of tires by car owners, due to the fact that underinflation can waste up to five percent of a car’s fuel by the increase of car-road friction, can substantially boost their fuel efficiency.

Answer: More wordy than B. And is passive.

(E) Because up to five percent of a car’s fuel are wasted through the increases in car-road friction when the tires are underinflated, car owners properly inflating tires can substantially boost their fuel efficiency.

Answer: First line uses are should be is

In this question as because is used , this means that something is cause of something OR because of something someone is doing something.

(A) Car owners who inflate their tires properly can substantially boost their vehicles’ fuel efficiency, since the increase in car-road friction can waste up to five percent of car fuel by underinflation.

> Firstly is seems like car owners are inflating their tires and not of their cars and this is illogical.

> secondly the statement is not correct in the use of since as true reason is not rectified as it is in option "B"

(B) Because the underinflation of tires can waste up to five percent of a car’s fuel by increasing car-road friction, car owners can substantially boost their vehicles’ fuel efficiency by properly inflating the tires.

> Because underinflation waste car's fuel , car owners can ----------------. Correct use of words.

(C) Their vehicles’ fuel efficiency is substantially boosted by car owners through the proper inflation of tires that, when underinflated, can waste up to five percent of car fuel by an increase in car-road friction.

> Awkward construction

(D) The proper inflation of tires by car owners, due to the fact that underinflation can waste up to five percent of a car’s fuel by the increase of car-road friction, can substantially boost their fuel efficiency.

> Awkward construction

(E) Because up to five percent of a car’s fuel are wasted through the increases in car-road friction when the tires are underinflated, car owners properly inflating tires can substantially boost their fuel efficiency.

> Awkward construction

OA is B.
Please note that having read A and B, we can figure out that these sentences aim to describe a solution to a specific situation.

(A) Car owners who inflate their tires properly can substantially boost their vehicles’ fuel efficiency, since the increase in car-road friction can waste up to five percent of car fuel by underinflation.
This option first described a fact, then explained its reasons. However, that is not what we want to say.

(B) Because the underinflation of tires can waste up to five percent of a car’s fuel by increasing car-road friction, car owners can substantially boost their vehicles’ fuel efficiency by properly inflating the tires.
Correct. The sentence first depicted a specific situation, then described its solution. That is exactly what we want.

(C) Their vehicles’ fuel efficiency is substantially boosted by car owners through the proper inflation of tires that, when underinflated, can waste up to five percent of car fuel by an increase in car-road friction.
Awkward sentence.
Feel really tired to remember and understand the first half of the sentence already!

(D) The proper inflation of tires by car owners, due to the fact that underinflation can waste up to five percent of a car’s fuel by the increase of car-road friction, can substantially boost their fuel efficiency.
Awkward sentence.
Same as C.

(E) Because up to five percent of a car’s fuel are wasted through the increases in car-road friction when the tires are underinflated, car owners properly inflating tires can substantially boost their fuel efficiency.
Awkward sentence.
Same as C.

Option Elimination -

(A) Car owners who inflate their tires properly can substantially boost their vehicles’ fuel efficiency, since the increase in car-road friction can waste up to five percent of car fuel by underinflation. - Car owners with tyres - wrong.

(B) Because the underinflation of tires can waste up to five percent of a car’s fuel by increasing car-road friction, car owners can substantially boost their vehicles’ fuel efficiency by properly inflating the tires. - perfect

(C) Their vehicles’ fuel efficiency is substantially boosted by car owners through the proper inflation of tires that, when underinflated, can waste up to five percent of car fuel by an increase in car-road friction. - Thier goes to Car owners. Saying Car owner's vehicles efficiency is substantially boosted by car owners - wrong

(D) The proper inflation of tires by car owners, due to the fact that underinflation can waste up to five percent of a car’s fuel by the increase of car-road friction, can substantially boost their fuel efficiency. "Due to" is an adjective phrase that modifies nouns or pronouns. It is used to explain the cause or reason for something. It is recommended to use "due to" only. The cancellation (NOUN) of the event was due to bad weather. The "Due to" adjective phrase modifies the noun "The cancellation" and explains the reason for "bad weather." "Because of" is a prepositional phrase that functions as an adverbial. It explains an ACTION or the reason for an ACTION.
Eg. The flight was delayed because of heavy traffic. Here, "Because of" explains the action of "delay," and the reason was " heavy traffic."

Here, due to introduces a relative clause - wrong.

(E) Because up to five percent of a car’s fuel are wasted through the increases in car-road friction when the tires are underinflated, car owners properly inflating tires can substantially boost their fuel efficiency. - S(Fuel -singular) Verb (Are plural)