Question

the principle characteristic distinguishing marine and freshwater ecosystems is ______.
a temperature
b presence of corals
c presence of fish
d dissolved salt

please select the best answer from the choices provided

○ a
○ b
● c
○ d

Explanation:

Marine ecosystems have high dissolved salt (salinity), while freshwater ecosystems have very low dissolved salt. Temperature, corals, and fish presence aren't the primary distinguishing factor. So the correct answer is related to dissolved salt.

Answer:

D. dissolved salt