Nephron is called structural and functional unit of kidney. Why?

Nephron is called structural and functional unit of kidney. Why ?
A. 1) Each kidney is made up of more than one million microscopic and thin tubular units called nephrons or uriniferous tubules. Hence nephron is known as structural unit of kidney.
2) Nephron’s chief function is to regulate the concentration of water and soluble sub-stances, reabsorbing what is needed and excreting the rest as urine. Hence it is known as functional unit of kidney.