A, the digestive tract from top to bottom is: mouth, pharynx, esophagus, stomach, small intestine, large intestine and anus. Correct.
B, the path of pulmonary circulation is: right ventricle → pulmonary artery → pulmonary capillary → pulmonary vein → left atrium. B correct;
C, the formation process of urine is: blood enters the renal capsule cavity through glomerular filtration to form original urine, and when the original urine flows through the renal tubule, it is reabsorbed by the renal tubule to form urine. C error;
D. The conduction path of reflex arc is: receptor → afferent nerve → nerve center → efferent nerve. Correct.
So choose: C.