This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Anatomy
True about adrenal pheochromocytoma is 
Select and explain. 
A. Chromaffin negative, B. Mostly malignant, C. Bilateral in 10 percnt cases, D. Unilateral in 10 percnt cases
C: Bilateral in 10 percnt cases
Answer: C: Bilateral in 10 percnt cases 
Explanation: Refernce Robbins page no 1134 The "10 percent rule" forpheochromocytoma/paraganglioma--10% familial, 10% malignant, 10% extra-adrenal--is therefore no longer tenable. Current roles of pathology are limited to diagnosing primary or metastatic tumors and identifying features suggestive of malignant potential or hereditary disease.