Granitic soil

[RonPurewal]

choice D contains no such structures.

if you're talking about choice E (and just wrote "D" by mistake)—
EVERYTHING ELSE in those constructions ("making..." vs "so as to cause...") is very clearly non-parallel. there's no reason to even pay attention to the not/nor.

[RonPurewal]

as for the other part of your post, it looks like you ... answered your own question?
(about absolute/relative)

please clarify if there is still a question there.

[AnkitG933]

Hi Ron,

Any idea why the correct choice includes singular verb at one end and plural at other.

so hard that it makes burrowing difficult or so soft that it could cause

[RonPurewal]

"could cause" can be either singular or plural (...in this case, singular).

[RAHULS852]

Your sentence IS hypothetical, so "could" is quite appropriate.

"Neither...nor" is the correct way to express the sentiment you're asking about, rather than "not...nor".

Hi Sage/ Manhattan expert,

I think "not ...nor" construction is not always wrong.
eg: One report concludes that many schools do not have, nor are they likely to have, enough computers to use them effectively.
Here parallelism occurs between "do not have...... nor are they likely to have"

Kindly check my reasoning.

Regards,
Rahul Singh

[Sage Pearce-Higgins]

I agree with you that the construction "not...nor" can be correct. However, in the context of the example above, "neither... nor..." is the correct option. Why? That's a tricky question. I'm thinking that 'not...nor' needs a negative verb at the start of the construction.