Final answer:
The RPO position in an IVU is used to demonstrate the right kidney parallel to the IR. The left kidney is demonstrated in the LPO position. Therefore, options 1 and 3 are correct.
Step-by-step explanation:
The RPO position in an intravenous urogram (IVU) is used to demonstrate the right kidney parallel to the imaging receptor (IR). In this position, the kidney is tilted towards the right side of the body, allowing for a clear visualization of the right kidney. The left kidney, on the other hand, is demonstrated when the patient is in the left posterior oblique (LPO) position, which tilts the kidney towards the left side of the body. Therefore, the correct answer is option D, 1 and 3 only.