A commensal bacterium does not infect its host, which is option D. Details about commensalism can be found below.
<h3>What is commensalism?</h3>
Commensalism is a kind of relationship that involves the sharing of the same environment by two organisms where one species benefits and the other is unaffected.
For example, barnacles on whales is a commensalistic relationship.
According to this question, a commensal bacterium will not affect or harm it's host by infect it neither will it benefit its host.
Learn more about commensalism at: brainly.com/question/14224704
#SPJ1
I believe the correct answer is A) Silurian period occurred before the Neogene era, because the other answer are wrong.
Hadean eon ended before Silurian period.
Mesozoic and Permian era were after Silurian period.