**Core Concept**
Endemic bladder stones are a type of urinary tract stone that occurs in specific geographic regions, particularly in areas where the diet is cereal-based and the water is hard. These stones are often associated with malnutrition, particularly a lack of animal protein and vitamin B12.

**Why the Correct Answer is Right**
The correct answer is that endemic bladder stones are not always associated with recurrence. In fact, many cases of endemic bladder stones are asymptomatic and do not recur. The recurrence rate of endemic bladder stones is not as high as other types of urinary tract stones. This is because the underlying cause of endemic bladder stones, such as malnutrition, can be addressed through dietary changes.

**Why Each Wrong Option is Incorrect**
**Option B:** High incidence in cereal-based diet - This statement is true. Endemic bladder stones are more common in areas where the diet is cereal-based, which is often associated with a lack of animal protein and vitamin B12.
**Option C:** Peak incidence in 3 years old children in India - This statement is also true. Endemic bladder stones are most commonly seen in young children in India, particularly those between the ages of 3 and 5.
**Option D:** Most common type is ammonium urate or calcium oxalate - This statement is true as well. The most common types of endemic bladder stones are ammonium urate and calcium oxalate stones.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that endemic bladder stones are often associated with malnutrition and can be prevented through dietary changes. A diet rich in animal protein and vitamin B12 can help prevent the formation of these stones.

**✓ Correct Answer: A. Always associated with recurrence**