Catelin has had a slow throbbing pain in her ankle since she twisted it while in-line skating last week.Where are these pain signals travelling

A)  along thin, unmyelinated C fibres 
B)  through periacqueductal gray neurons in the midbrain 
C)  along ungated endorphin pathways in the hypothalamus 
D)  through thick, myelinated A-delta fibres

Unmyelinated C Fibres

Nerve fibers lacking a myelin sheath, involved in transmitting slow-conducting pain and temperature sensations.

Myelinated A-Delta Fibres

Fast-conducting nerve fibers wrapped in myelin sheath that transmit sharp, immediate pain signals to the brain.

Throbbing Pain

A type of pain characterized by a pulsating sensation, often in sync with the heartbeat, and usually indicative of inflammation or other underlying conditions.