In human anatomy, the urinary system plays a vital role in removing waste and excess fluids from the body. It consists of various structures, including the kidneys, ureters, bladder, and urethra. The kidneys, in particular, are responsible for filtering the blood and producing urine.

Within each kidney, there are tiny structures called nephrons, which are responsible for the filtration process. The nephrons consist of a renal corpuscle and a renal tubule. The renal tubule is further divided into several segments, including the proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct.

The collecting ducts merge to form larger structures called papillary ducts or ducts of Bellini. These ducts empty urine into the minor calyces, which are cup-like structures that surround the renal papillae. The minor calyces collect urine from several papillary ducts and transport it to the major calyces.

The minor calyces are smaller in size compared to the major calyces. They usually have a number that is equal to the number of renal pyramids present in the kidney. Hence, the correct answer to the given question is option 'C': Equal to pyramid number.

The renal pyramids are cone-shaped structures in the kidney that contain the nephrons. They are arranged in a triangular pattern, with the base facing towards the cortex and the apex pointing towards the renal sinus. Each pyramid is associated with one or more minor calyces.

It is important to note that the number of minor calyces can vary from person to person, as it depends on the number of renal pyramids present in the kidney. On average, a human kidney has 8 to 14 renal pyramids, which corresponds to the number of minor calyces.

In conclusion, the number of minor calyces in the human kidney is equal to the number of renal pyramids. This arrangement allows for the efficient collection and transport of urine from the papillary ducts to the major calyces, eventually leading to the bladder for elimination.