Which of these is a biotic factor of an aquarium ecosystem?

a: algae growing on the glass
b: gravel on the bottom of the aquarium
c: temperature of the water
d: amount of oxygen in the water

Kelly has come up with an explanation for why her sister is sometimes in a good mood and other times in a bad mood. she speculates that it is based on the hours of sleep her sister got the previous night. this explanation for her sister's behaviors is an example of a(n)