Answer: Spinal cord (and sometimes brain) without conscious thought.
- A The brain alone, processing input before any response
- B Spinal cord (and sometimes brain) without conscious thought
- C Conscious decision-making in the cerebral cortex
- D Only motor neurons, with no sensory input required
Correct answer: B. Spinal cord (and sometimes brain) without conscious thought
Explanation: A reflex arc is a quick automatic response. Simple spinal reflexes bypass the brain: receptor → sensory neuron → spinal cord → motor neuron → effector.
Structure of a neuron. Image: LadyofHats (Mariana Ruiz), Public Domain, via Wikimedia Commons.
Concept context
Brain, spinal cord, neurons, reflex arcs, and sense organs.