Final answer:
The outer part of the kidney is known as the renal cortex, which houses all of the nephrons, the functional units responsible for blood filtration and urine formation. The correct option is 2.
Step-by-step explanation:
The outer part of the kidney is called the renal cortex. This region contains all of the nephrons, which are the functional units of the kidney. Within the renal cortex, you'll find important structures such as the glomerulus and Bowman's capsule, as well as the proximal and distal convoluted tubules of the nephrons.
Some nephrons also have loops of Henle that extend deep into the adjacent area of the medulla, involved in the concentration of urine. The renal cortex is essential for the filtration of blood and the initial steps in urine formation. Hence, 2 is the correct option.