In each one of the following sets of body parts or substances or 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.

(a) ultrafiltration

Ultrafiltration occurs at the barrier between blood plasma and the filtrate in the glomerular capsule (that contains the Bowman’s capsule). This process leads to the formation of glomerular filtrate.

(b) excretion

All the rest of the terms are organs involved in excretion.

(c) osmoregulation

One of the functions of the kidneys is to keep a check on the composition of the blood. This process is triggered by the ADH that is secreted by the pituitary. It regulates the tonicity of body fluids - checks the water and urine levels.

(d) excretion

The rest of the terms are the end products of excretion.