What best defines isosthenuria, and what leads to this condition?
Group of answer choices
A. Isosthenuria is the inability to concentrate or dilute urine properly, and it is caused by a loss of papillae.
B. Isosthenuria is a symptom of diabetes mellitus, and it is caused by an increase in papillae.
C. Isosthenuria is a condition of excessive urine concentration, and loss of papillae leads to increased concentrating ability.
D. Isosthenuria is a normal urine concentration regardless of fluid intake, and it is caused by an increase in papillae.