Filtration of blood takes place at Malpighian body. Malpighian body or corpuscle comprises of glomerulus and Bowman's capsule. Filtration of blood takes place in glomerulus through glomerular filtration. Therefore, option 'D' is the correct answer.

Filtration of blood takes place at:

The process of filtration in the kidney occurs at the Malpighian body, which is composed of the glomerulus and Bowman's capsule. The glomerulus is a network of tiny blood vessels called capillaries, and Bowman's capsule is a cup-shaped structure that surrounds the glomerulus.

Explanation:

1. Malpighian body:
The Malpighian body, also known as the renal corpuscle, is the site of filtration in the kidney. It consists of the glomerulus and Bowman's capsule. The glomerulus is a tuft of capillaries that receives blood from the afferent arteriole and filters it. Bowman's capsule surrounds the glomerulus and collects the filtrate.

2. Filtration process:
The filtration of blood takes place in the glomerulus. Blood enters the glomerulus through the afferent arteriole and leaves through the efferent arteriole. The high pressure in the glomerulus forces water, ions, and small molecules to pass through the walls of the capillaries into Bowman's capsule. This process is known as ultrafiltration.

3. Filtration membrane:
The filtration membrane in the glomerulus consists of three layers: the endothelium of the glomerular capillaries, the basement membrane, and the podocytes of Bowman's capsule. These layers act as a sieve, allowing small molecules like water, ions, glucose, amino acids, and waste products to pass through while preventing larger molecules like proteins and blood cells from entering the filtrate.

4. Filtrate formation:
The filtrate that is formed in Bowman's capsule contains water, ions, glucose, amino acids, urea, and other small molecules. It is similar in composition to the blood plasma but lacks larger molecules like proteins. The filtrate then enters the renal tubules, starting with the proximal convoluted tubule (PCT).

5. Proximal convoluted tubule (PCT):
After filtration, the filtrate passes through the PCT, where reabsorption of water and useful substances occurs. The PCT is responsible for reabsorbing most of the filtered water, glucose, amino acids, and ions back into the bloodstream. This reabsorption process helps maintain the body's water balance and prevents the loss of essential nutrients.

In conclusion, the filtration of blood takes place at the Malpighian body, specifically in the glomerulus. This process involves the passage of water, ions, and small molecules through the filtration membrane into Bowman's capsule. The resulting filtrate then enters the renal tubules, starting with the proximal convoluted tubule (PCT), where further reabsorption and processing occur.