Blood

The glomerulus is a network of tiny blood vessels located within the kidney's nephrons. It is the initial site of blood filtration in the kidney. Blood pressure forces fluid and small solutes, such as water, electrolytes, and waste products, out of the glomerular capillaries and into the Bowman's capsule, which surrounds the glomerulus.

This process is known as glomerular filtration and is the first step in urine formation. The filtered fluid, known as the glomerular filtrate, then undergoes further processing in the renal tubules, including reabsorption and secretion, to eventually form urine.

Therefore, the correct answer is (A) Glomerulus.

Neutrophils are a type of granulocyte and are the most common type of WBC found in the human body. They play a crucial role in the immune response, particularly in defending against bacterial infections. Neutrophils are highly mobile and are among the first cells to arrive at the site of infection or inflammation.

While all the options listed are types of WBCs, neutrophils are the most abundant, accounting for approximately 55-70% of the total WBC count in a healthy individual.

Therefore, the correct answer is (C) Neutrophils.