Dialysis patients, who will have blood withdrawn, dialyzed, then replaced, are always weighed when they enter the facility and then weighed carefully again before they leave, because

A) even small changes in body weight may signify changes in blood volume and therefore blood pressure.
B) many people who have dialysis are diabetic and must control their weight carefully.
C) dialysis removes blood proteins and these weigh more than other blood components.
D) dialysis is likely to cause edema and such swelling must be controlled.
E) reclining posture during dialysis can cause a tendency for weight gain.