. In each of the following sets of body parts

In each of the following sets of body parts/substances/processes, pick out the one item which overall includes the remaining four
(a) Glomerular filtrate, Bowman's capsule, ultrafiltration, glomerulus, blood plasma.
(b) Skin, liver, lungs, kidneys, excretion.
(c) ADH, water, pituitary, osmoregulation, urine.
(d) CO2, bile pigments, water, excretion, urea.