as high as should always be followed by one value.(D out)
usage of that of is wrong (B, E out)

eg :The building is as high as 360ft
not The building is as high as 360ft- 370ft.

Also, Its the framework that is bannked with dirt.So it will become .... its framework of poles overlaid with slabs ................ and banked with dirt ............

Usage of them in option C is not correct, not able to make out whther its going to poles or slabs


IMO A

This is QID 2185 in the GMATFix Solutions Engine (full solution here).

To pick between "banked" and "was banked", realize that we're describing the framework of poles.

"its framework of poles overlaid... and banked". eliminate C, D and E.

A) framework...banked with dirt to a height of 3ft
B) framework...banked with dirt as high as that of 3ft.

In B, it's unclear what "that" refers to. It has no antecedent.
[spoiler]
answer A[/spoiler]

The single-family house constructed by the Yana, a Native American people who lived in what is now northern California, was conical in shape, its framework of poles overlaid with slabs of bark, either cedar or pine, and banked with dirt to a height of three to four feet.

A) banked with dirt to a height of

B) banked with dirt as high as that of
INCORRECT; sentence is not comparing height

C) banked them with dirt to a height of
INCORRECT; framework of poles is already the subject.. so them is redundant..

D) was banked with dirt as high as
INCORRECT; Absolute Phrase do not have Verb

E) was banked with dirt as high as that of
INCORRECT; Absolute Phrase do not have Verb