The correct option is A Medulla
Kidneys are reddish brown, bean shaped structures. Towards the centre of the inner concave surface of the kidney is a notch called hilum through which ureter, blood vessels and nerves enter. Inner to the hilum is a broad funnel shaped space called the renal pelvis with projections called calyces.
Kidney is divided into two zones, an inner medulla and an outer cortex. Cortex is the zone that occupies the peripheral zone of kidneys. The medulla is the inner region of the of the kidney. It is divided into a few conical masses known as the renal or medullary pyramids projecting into the calyces.