The answer for this question would be Integument, digestive, respiratory and urogenital.
The largest system that contact with the external environment would be integument and digestive. That makes two system has normal flora of microbes and not sterile like the other systems. Normal flora of microbes will prevent the pathogen microbe grows so it gives some benefit.
Biotic means that it came from or has been produced/has been in relation with an organism. So your answer would be THE BACTERIA THAT LIVES IN THE INTESTINE OF A RABBT, it was the interaction of 2 things within them selves.
A chimpanzee because we’re related to monkey
I do not really know but i think that the answer is c but wait for other people
