The firing frequency of Group 1 muscle spindle afferents is highest during a change of muscle length, and the firing frequency of Group 2 muscle spindle afferents is highest when the muscle is longer. b. Golgi tendon organ afferent firing frequency increases when tension on the muscle increases. c. Muscle spindle reflex is an example of negative feedback; afferent sensory neuron detects stretch and the result is an efferent motor neuron activation that results in contraction. d. both a) and b) are correct, and c) is incorrect e. a), b) and c) are all correct