Final answer:
The common finding in cystitis and individuals passing kidney stones is hematuria, which refers to the presence of blood in the urine.
Step-by-step explanation:
The correct answer is option a. Hematuria. Hematuria refers to the presence of blood in the urine, which can be observed in both cystitis (inflammation of the bladder) and in individuals passing kidney stones. In both cases, minor damage to the inside walls of the kidney, ureter, and/or urethra can cause blood to appear in the urine. Although options b (hemoglobinuria) and c (myoglobinuria) involve the presence of abnormal substances in the urine, they are not typically associated with cystitis or kidney stones. Therefore, option a is the most common finding in both conditions.