Ms. Smith told her students to do 30 jumping jacks without stopping. When everyone had completed the jumping jacks, she asked the students to look around and observe each other. She said, "What do you notice about each other that is different from before you did the jumping jacks?" The changes that the students observed, rapid breathing and sweating, would be classified as a to a change in a system.
A) limit
B) response
C) stimulus
D) feedback mechanism