Answer: Increase Sensory Input (Rubbing, Touching, Feeling Cold Water etc) At the injury location
Explanation: The gate-control theory suggests that pain is sent through the spinal cord to the brain and along with sensory information, there are certain times where pain should be felt more than sensory inputs and vice versa. This comes into play when we talk about the 'gates,' or areas where the spinal cord and brain decide that pain or sensory input should be filtered out or enhanced. If the sensory information and pain information travel at the same time, it is thought that enough sensory information could lessen the feeling of pain; this is thought to be the cause of rubbing a scrapped knee or injury when we fall.
Anyways, since the choices weren't given, just know that any amount of sensory input near the injury location will reduce Gavin's experience of pain, according to the gate-control theory. I hoped this helped!