SC Question -Source Manhattan

Hi experts,

Can you please assist me in understanding the below question?

Because of 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 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
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


The OA is E. OE is - The phrase "difference between" correctly replaces "differences in." Additionally, the verb "ascend" is in the subjunctive mood. Finally, the singular pronoun "he" correctly refers to the singular "a diver."

My question is how do we see the mood of the verb -Ascend?
Also, how do we spot the subjunctive mood ?