The nephron is the microscopic structural and functional unit of the:

kidney

The correct answer is Option (1)- kidney

The nephron is the microscopic structural and functional unit of the kidney. Each kidney is composed of thousands of nephrons, which play a vital role in the filtration and purification of blood by removing waste products and excess substances, ultimately forming urine. The nephron consists of a renal corpuscle (containing the glomerulus and Bowman's capsule) and a renal tubule (comprising the proximal convoluted tubule, loop of Henle, and distal convoluted tubule). This intricate structure allows the kidneys to maintain fluid and electrolyte balance, regulate blood pressure, and eliminate metabolic waste from the body.