Final answer:
The true statement reflects how the brain uses the rate and number of sensory neurons firing to distinguish between different intensities of stimuli, affecting perception.
Step-by-step explanation:
The statement 'The brain may distinguish between stimulus intensities based on which sensory neurons are firing' is true. Sensory information is processed by the brain, where the intensity of a stimulus can be encoded by the rate of action potentials produced by sensory receptors.
A more intense stimulus will generate action potentials more rapidly, activating more receptors, while a less intense stimulus will do so at a slower rate and with fewer receptors. The brain integrates this information and is involved in perception, interpreting the sensory stimuli further at higher levels within the nervous system.