Select the best definition of Phrenic nerve.

A. A major nerve that passes through the carpal tunnel and supplies thenar muscles and sensation to the lateral hand. B. A normal narrowing where the ureter enters the urinary bladder and a common site of stone impaction. C. The motor nerve to the diaphragm, arising mainly from cervical roots C3 to C5. D. The principal nerve of the anterior thigh, supplying quadriceps and enabling knee extension.