Which of the Following Statements About the Protonephridia of Freshwater

Which of the following statements about the protonephridia of freshwater flatworms is CORRECT?

A) Fluid from the body enters the protonephridia without first being filtered.
B) Protonephridia are surrounded by a capillary network to allow for selective reabsorption and secretion.
C) The urine leaving the body of a freshwater flatworm is more concentrated than its body fluids.
D) Muscular contractions drive fluid movement through the excretory tubules.
E) The fluid passing through the tubules is not modified before excretion.