**Core Concept**
The commonest presentation of bilateral ureteric stones is related to the pathophysiology of urinary obstruction, which causes renal colic, flank pain, and sometimes urinary retention. The condition is often associated with recurrent episodes of renal colic due to intermittent obstruction.

**Why the Correct Answer is Right**
The correct answer is related to the mechanism of ureteric stones causing obstruction, leading to renal colic. Ureteric stones can cause intermittent obstruction of the ureter, resulting in recurrent episodes of renal colic, flank pain, and sometimes urinary retention. This is due to the stone's movement through the ureter, causing intermittent obstruction and subsequent pain.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the commonest presentation of bilateral ureteric stones. While hematuria (blood in the urine) can be a symptom, it is not the most common presentation.
**Option B:** This option is incorrect because it describes a complication of bilateral ureteric stones, rather than the commonest presentation.
**Option C:** This option is incorrect because it describes a condition that can be associated with bilateral ureteric stones, but it is not the most common presentation.

**Clinical Pearl / High-Yield Fact**
One important point to remember is that the presence of bilateral ureteric stones can lead to recurrent episodes of renal colic, which can be triggered by various factors such as movement, dehydration, or certain medications. This is a classic exam trap, and students should be aware of the potential for intermittent obstruction and recurrent pain.

**Correct Answer: C. Recurrent renal colic**