please help

Read the paragraph from the section "Sub-Disciplines Of Oceanography."

Oceanography's diverse topics of study are generally categorized in four major sub-disciplines. A sub-discipline is a specialized field of study within a broader subject or field of study. Oceanographers specialize in the biological, physical, geological and chemical processes of the marine environment.

Why did the author use the word "diverse"?

A
to emphasize the specialized knowledge that all oceanographers must learn while in school
B
to emphasize the various interests and careers that fall under the category of oceanography
C
to illustrate that anyone can become an oceanographer if they have an interest in protecting the ocean
D
to illustrate that it is difficult to choose which discipline of oceanography to study