The filtration units of kidneys are called

The correct option is D

Nephrons

The correct option is D.

Explanations for the correct options:

1. The nephron is the functional unit of the kidney that is involved in urine production.
2. It is a long tubule that contains a Bowman's capsule that encloses the capillaries referred to as glomerulus.
3. The capsule and glomerulus together are referred to as the renal corpuscle.
4. Its primary function is to remove waste materials from the blood and forms urine.

Explanations for the incorrect options:

Option A:

The ureter is a tubular structure that carries urine from the kidneys to urinary bladders.

Option B:

The urethra is the tube that passes urine out of the body and runs along the penis. It is also in the ejection of semen.

Option C:

Neurons are the fundamental units of the nervous system and are responsible for the sensory input and sending motor commands to muscles.

Final answer: The filtration units of kidneys are called nephrons.