**Core Concept**
A flower vase pattern of the pelvis in an intravenous urogram is a radiological finding associated with pelvic fractures, particularly those involving the sacrum and pubic rami. This pattern is due to the displacement of the pelvic structures, which can cause a characteristic appearance on imaging.

**Why the Correct Answer is Right**
The flower vase pattern is classically seen in patients with a type C pelvic ring injury, which involves a disruption of the sacroiliac joint and the pubic rami. This type of injury can cause a displacement of the pelvic structures, leading to a characteristic "flower vase" appearance on an intravenous urogram. The sacrum and pubic rami are displaced, causing a narrowing of the pelvic canal and a characteristic "vase" shape.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because a type A pelvic ring injury is a stable fracture, and would not typically cause a flower vase pattern.
* **Option B:** This option is incorrect because a type B pelvic ring injury is an unstable fracture, but the flower vase pattern is more specifically associated with type C injuries.
* **Option C:** This option is incorrect because while it is a type of pelvic fracture, it is not specifically associated with the flower vase pattern.

**Clinical Pearl / High-Yield Fact**
In the context of a pelvic fracture, it is essential to remember that the pattern of injury (stable vs. unstable) can have significant implications for patient management and outcome. A type C pelvic ring injury, which is associated with the flower vase pattern, requires prompt and aggressive management to prevent complications.

**Correct Answer: C. Type C pelvic ring injury.**