Why should a person who sells fish and fish aquaria learn about the excretory systems in animals?
a. So that they can understand how gastrointestinal disease spread among aquatic animals
b. So that they can get a license to sell exotic fish
c. So that they can maintain the salinity (amount of salt) of their aquaria to keep their aquatic animals healthy

C. So that they can maintain the salinity (amount of salt) of their aquaria to keep their aquatic animal healthy.

Hope this helps!

Please mark brainliest!

option d is correct. corroborated sources of historical evidence   is necessary to validate a claim about an event in history.

historians tend to use written sources, but audio and visual materials as well as artifacts are important objects that supply information to modern historians.

historical sources are usually divided into two categories: primary and secondary sources. depending on the historian's intent, some sources shift their designation. determining what type of sources toimplement, and the level of credibility and reliability of those sources, is a significant step in critical thinking for the historian.

explanation: