Final answer:
The correct sequence in a reflex arc involves the signal traveling from a sensory receptor, through the CNS to interneurons, then to motor neurons, and finally to effectors.
Step-by-step explanation:
The correct sequence of events in a reflex arc is option b: Sensory receptor to CNS to interneurons to motor neurons to effectors. A sensory receptor responds to a stimulus and sends a nerve impulse through a sensory nerve to the spinal cord. Once in the spinal cord, the signal is passed to an interneuron, which then transfers the impulse to a motor neuron. This motor neuron relays the impulse to an effector, such as a muscle, causing it to contract.