**Core Concept**
The management of renal stones depends on their size, location, and the presence of obstruction. In patients with stones in the renal pelvis without hydronephrosis, the primary goal is to manage pain and prevent complications.

**Why the Correct Answer is Right**
The correct answer involves managing the patient's pain and preventing complications associated with renal stones. A 3 cm stone in the renal pelvis is considered a moderate-sized stone and can cause significant pain. The patient should be managed with analgesics and adequate hydration to help pass the stone. In some cases, alpha-blockers like tamsulosin may be prescribed to help relax the smooth muscle in the ureter and facilitate stone passage. However, in this case, the stone is in the renal pelvis, and the use of alpha-blockers is not recommended.

**Why Each Wrong Option is Incorrect**
**Option A:**
This option may be considered if the patient has a large stone causing obstruction or if the stone is not passing with conservative management. However, it is not the most appropriate initial management for a 3 cm stone in the renal pelvis without hydronephrosis.

**Option B:**
This option may be considered if the patient has a history of kidney stones and is at high risk for future stone formation. However, it is not the most appropriate management for a patient presenting with a single stone that is not causing obstruction.

**Option C:**
This option may be considered if the patient has a ureteral stone causing obstruction. However, in this case, the stone is in the renal pelvis, and the use of a ureteral stent is not indicated.

**Clinical Pearl / High-Yield Fact**
It is essential to differentiate between renal and ureteral stones, as their management differs. Renal stones in the renal pelvis without hydronephrosis can often be managed conservatively, while ureteral stones may require more aggressive management.

**Correct Answer: D.**