Brendan’s uncle uses a dialysis machine each week. Since Brendan’s uncle’s kidneys are not working properly, the machine does most of their work for them. What do you think happens when a person’s kidneys are not working properly?
A. The person cannot filter waste from the blood.
B. The person cannot excrete urine.
C. The person is not able to absorb enough nutrients.
D. The person is not able to produce any waste materials.