Identify a change in your environment that might affect homeostasis explain using the terms stimulus, control center, set point, receptors, effectors, and imbalance in your answer

Which of the following must be true for a fossil organism to be useful as an index fossil? a. the fossil organism must be widespread geographically. b. the fossil organism must be abundant. c. the fossil organism must be limited to a short span of geologic time. d. all of the above.