This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
All are true about thymus swelling except – 
Select and explain. 
A. Widening of mediastinum on X–ray, B. Sharp border with sail like appearance, C. Steroid administration reduces size of swelling, D. Shift of trachea on X–ray
D: Shift of trachea on X–ray
Answer: D: Shift of trachea on X–ray 
Explanation: Thymic shadow does not indent tracheal shadow. A mediastinal shadow indenting tracheal shadow should always be evaluated for a significant pathology.
Thymic swelling may cause widening of anterior mediastinum. Thymic swelling causes a sail-shaped shadow. Thymic swelling may shrink with use of steroids.