Although unhappy with the high rent her company was paying

I eliminated A,B and C based on the absence of "that while D on the presence of "there" (at the end). Can anybody tell me if my approach was correct or not?

Are A, B and C incorrect only because of missing "that".
Can some expert help me to understand the structure of A, B and C

Although energy prices have tripled in the United States over the last two years, research indicates few people to
have significantly reduced the amount of driving they do, nor are they making fuel efficiency a priority when
shopping for cars.

A. few people to have significantly reduced the amount of driving they do, nor are they making
B. few people having significantly reduced the amount of driving they do or made
C. that there are few people who have significantly reduced the amount of driving they do, nor having made
D. that few people have significantly reduced the amount of driving they do and are not making
E. that few people have significantly reduced the amount of driving they do or made

Indicates that… A, B out
C: not having made is not parallel to anything else.
Between D and E:
There's a problem of meaning here. Let me illustrate with an analogy.
Few of these animals eat or drink during the harsh daylight hours
--> this sentence would mean that the animals
do neither of these activities, in the main, during daylight hours.
few of these animals eat and avoid drinking during the harsh daylight hours
--> the sentence would mean that
there are few animals that do both of these things, but leaves open the possibility that many, or perhaps even a
majority, do one or the other. Also, this wording is hopelessly awkward, but it probably takes a native speaker's
ear to discern that fact.
the last two choices of the problem exhibit the same sort of issue. The intended meaning is that people are doing
either of these activities, so (e) is the only one of these two choices to correctly represent this meaning
E says: that few people have significantly reduced the amount of driving they do or made
Here…
“have significantly reduced” OR “(have significantly) MADE”… May not look parallel but are absolutely parallel.
“The amount of driving they do” is just a NOUN… so don’t try to make DO parallel to anything.
they're using it idiomatically here. you can "do a lot of driving", in the same way you can "do a lot of homework".
do notice that the identical construction appears in all five choices, so that it's actually irrelevant to the solution of
the problem.
yes, "do that amount of driving" is the idea here.

Although unhappy with the high rent her company was paying for its suburban office building, the chief executive recognized rental rates for buildings in the suburbs as far lower than it typically is for property that is located within the city limits.

(A) rental rates for buildings in the suburbs as far lower than it typically is for property that is located within the city limits - that is needed; as far lower than is incorrect
(B) rental rates for buildings in the suburbs as being far lower than what the rates typically charged within the city limits had been for property located there - same as A ; as being far lower than is incorrect
(C) rental rates typically being charged for property located within the city limits to be far lower as they typically were within the city limits for the property there - same as A
(D) that rental rates for buildings in the suburbs were far lower than rental rates typically being charged within the city limits for property located there -being and redundant
(E) that rental rates for buildings in the suburbs were far lower than those typically charged for property located within the city limits - Correct

Answer E

On another note, in my view, usage of "as" in some other options is incorrect because "as" is used to introduce a new clause and in this usage it means: because.

(D) that rental rates for buildings in the suburbs were far lower than rental rates typically being charged within the city limits for property located there
(E) that rental rates for buildings in the suburbs were far lower than those typically charged for property located within the city limits.

Please explain the meaning difference:
within the city limits for property located there
and
property located within the city limits.

(D) that rental rates for buildings in the suburbs were far lower than rental rates typically being charged within the city limits for property located there
(E) that rental rates for buildings in the suburbs were far lower than those typically charged for property located within the city limits.

Please explain the meaning difference:
within the city limits for property located there
and
property located within the city limits.

(D) that rental rates for buildings in the suburbs were far lower than rental rates typically being charged within the city limits for property located there
(E) that rental rates for buildings in the suburbs were far lower than those typically charged for property located within the city limits.

Please explain the meaning difference:
within the city limits for property located there
and
property located within the city limits.