**Core Concept**
Proprioception is the sense of the relative position of one's own parts of the body and strength of effort being employed in movement. It is mediated by proprioceptors, specialized sensory receptors found in muscles, tendons, and joints, which transmit signals to the central nervous system.

**Why the Correct Answer is Right**
Proprioception is primarily carried by large, myelinated Aα fibers, which are responsible for transmitting signals from proprioceptors to the spinal cord and brainstem. These fibers have a diameter of 12-20 μm and a conduction velocity of up to 120 m/s. The Aα fibers are essential for motor coordination, balance, and posture.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Aα fibers are not responsible for transmitting pain or temperature sensations, which are carried by Aδ and C fibers, respectively.
**Option B:** This option is incorrect because Aβ fibers are primarily involved in transmitting touch and pressure sensations, not proprioception.
**Option C:** This option is incorrect because Aδ fibers are involved in transmitting pain and temperature sensations, not proprioception.

**Clinical Pearl / High-Yield Fact**
Remember that the loss of proprioception can lead to ataxia, a disorder of coordination and balance, as seen in conditions such as peripheral neuropathy or cerebellar lesions.

**Correct Answer: A. Aα fibers**