Final answer:
Postmicturition radiography in routine excretory urography is used to demonstrate the presence of tumor masses and the amount of residual urine, but not specifically for prostatic enlargement.
Step-by-step explanation:
Postmicturition radiography of the bladder during routine excretory urography is important as it helps to demonstrate various conditions. The main purposes are to visualize the presence of tumor masses, assess the amount of residual urine, and provide information on the size and shape of the bladder which may suggest prostatic enlargement. The correct answer to the question 'Routine excretory urography usually include a postmicturition radiography of the bladder. This is done to demonstrate: 1. Tumor masses 2. Residual urine 3. Prostatic enlargement' would be C. 1 and 2 only.