You touch a hot stovetop by accident and quickly pull your hand away. The feeling of the hot temperature was carried from your hand to your spinal cord by what part of a reflex arc? A. Sensory neuron
B. Dorsal root
C. Interneuron
D. Motor neuron

(I am stuck between A and C)

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.