Because of differences in the humans body's internal

What is the OA for this? Between C & E, I will go with C as Ascends is singular

I don't want to reveal the OA so early but all I can say is the answer is between C and E

I believe the right idiom is ‘difference between X and Y’..

C does not provide this option. E does.

Yep, the idiom in choice E looks good but how about the plural verb ascend? "that" introduces a clause and hence diver become the subject (which is singular) so it need singular verb ascends.
This is the only reason I am going with C (unless the question is posted correctly with no typo)

Please explain your rationale on the subj-verb relationship in choice E.

I will go with C

the difference in the human body's internal pressure and that of the ocean is correct.... all it says is that internal pressure is different for both ocean and human body....

Also ascends correctly fit with the singular he....

regards,

Amardeep

Because of differences in the humans body's internal pressure and the ocean's, it is essential that a diver returning to the surface ascends slowly or they will suffer a painful condition known as the "bends."

a)differences in the human body's internal pressure and the ocean's, it is essential that a diver returning to the surface ascends slowly or they

b)the difference between the human body's internal pressure and the ocean's, it is essential that a diver returning to the surface ascend slowly or they

c)the difference in the human body's internal pressure and that of the ocean, it is essential that a diver returning to the surface ascends slowly or he -- What does "that" refer to: difference or pressure ?

d)differences in the human body's internal pressure and that of the ocean, it is essential that a diver returning to the surface ascend slowly or they

e)the difference between the internal pressure of the human body and that of the ocean, it is essential that a diver returning to the surface ascend slowly or he-- Correct

In E the comparison between internal pressure of the human body and that of the ocean is correctly worded. Also "ascend" is correct verb form - subjunctive mood.

C .. correct pronoun 'he' ....also uses ascends instead of ascend..

OA is E.

It is a special structure in subjunctive mood(unreal condition).Pay attention to the following structures:
It is necessary that.....
It is essential that....
it is important that....
It is strange that....
It is natural that .....
and so on
Remember in the above mentioned structures, after "that...", it should be followed by that + subject+should +bare infinitive (original form), but “shouldâ€

One more for E.

I believe ASCEND is right here. I remember to have read this construct in Manhattern SC guide.

If E turns out to be OA then I will digg in and find out.

Oh there you go faifai0714...subjunctive mood...thats what it is. yeeeeeeeyyy