Which statement most accurately describes Portal vein?

A. A vessel that carries nutrient-rich blood from the gastrointestinal tract to the liver. B. The principal nerve of the anterior thigh, supplying quadriceps and enabling knee extension. C. The motor nerve to the diaphragm, arising mainly from cervical roots C3 to C5. D. A network of spinal nerve roots C5 to T1 that supplies the upper limb.