What is the definition of marine biology?

I - Marine biology is the science that studies living beings that inhabit marine ecosystems, as well as the conservation of marine life, its biological elements, flora, and fauna.
II - Marine biology is the study of the characteristics of the sea, including knowledge of geology, geography, chemistry, physics, and biology that, in a correlated way, characterize the marine environment.
III - Marine biology is the term that defines the wide variety of living beings within this environment and the genes that inhabit them.
a) Only I is correct.
b) Only II is correct.
c) Only III is correct.
d) I, II, and III are correct.