Final answer:
The gate control theory of pain characteristic that suggests nonpainful stimuli can block pain impulses corresponds to choice (a). Pain perception involves nociceptive signals reaching the cerebral cortex, delayed due to the propagation of the axon potential. Mechanically and temperature-gated channels contribute to sensory input.
Step-by-step explanation:
The correct identification of the characteristic of the gate control theory of pain is that the theory suggests when a large volume of nonpainful stimuli are competing for the gate, pain impulses may be blocked. This is described in choice (a). This theory postulates that nonpainful input closes the "gates" to painful input, which prevents pain sensation from traveling to the central nervous system. Therefore, stimulation by non-noxious input is able to suppress pain.
Nociception begins at the sensory receptors, but pain perception does not start until the signals have reached the brain. The propagation of the axon potential is involved in transmitting these signals from the site of injury through the nervous system to the brain. Most axons carrying nociceptive information project to the thalamus, undergoing further processing in the primary somatosensory cortex. This process takes time, which may cause a delay in the conscious perception of pain.
Mechanically gated channels also play a role in the sensation of pain. These channels open in response to physical distortion of the cell membrane, such as when pressure is applied to the skin. Similarly, temperature changes can also activate temperature-gated channels.