This is because you have to let your food digest a bit before continuing your work out to prevent cramps and this like that.
Cnidarians were the first phylum that scientists saw tissue level organization in. Tissue level organization meaning cells all of one type start to function in a unified way.
B. I think I'm not so sure but that's my best guess.
The population of the mice would most likely increase. This is because the number of predators of mice will decrease. Predators are those that feed on others, in this case mice. When predators decrease, the prey (which would be the mice) will be able to populate thus leading to an increase in population.
