The correct answer is option Sensory neuron.
The dorsal root neurons control the sensory function of the body. In case, the dorsal root nerve is damaged, it results in the loss of the sensory function.
The dorsal root neuron carries the message from the body or the peripheral nervous system to the sensory nervous system. So, in the given case, the injury to the dorsal root of a reflex arc would result in the loss of the sensory functions of the arm.
