Students set up a controlled experiment. They put five crickets in each of three identical containers. They set one container to 15C, one to 20C, and another to 25C. Then they count the number of cricket chirps in each container during one hour. What are TWO constants in this experiment?

A:The temperature of each container
B:the number of crickets in each container
C:The kind of containers used
D:The number of cricket chirps.

22. the top of a cliff is located a distance h above the ground. at a distance h/2 there is a branch that juts out from the side of the cliff, and on this branch a bird's nest is located. two children throw stones at the nest with the same initial speed, one stone straight downward from the top of the cliff and the other stone straight upward from the ground. in the absence of air resistance, which stone hits the nest in the least amount of time?