Annelids have highly coiled tubules called nephridia which are involved in the removal of waste. The waste is discharged into the gut or the exterior through the nephridiopore. The nephridia in some of the annelids are of three types i.e., the pharyngeal, integumentary, and septal nephridia.The septal and pharyngeal nephridia open into the gut and, thus, are called enteronephric types. This helps to conserve maximum water through the process of reabsorption when waste passes through the gut.Thus, the correct answer is option A.