Final answer:
Calcium oxalate stone formation is facilitated by hypercalciuria, which is the increased urinary excretion of calcium that can lead to the formation of stones when combined with oxalate.
Step-by-step explanation:
The correct answer to the question regarding the facilitation of calcium oxalate stone formation is a. hypercalciuria. Hypercalciuria is defined as the urinary excretion of calcium by the kidneys. An increase in the level of calcium in the urine can lead to the formation of calcium oxalate stones, as the calcium can combine with oxalate to form the stone. It is not facilitated by hypoparathyroidism, low urine pH, or protein intake, although other factors such as diet, metabolic issues, and certain diseases can contribute to the risk of kidney stone formation.