**Core Concept**
The Focused Abdominal Sonogram for trauma (FAST) is a bedside ultrasound examination used to quickly identify free intraperitoneal fluid in patients with blunt thoraco-abdominal trauma. It involves scanning four specific regions to detect signs of bleeding or fluid accumulation.

**Why the Correct Answer is Right**
The FAST examination involves placing the ultrasound probe in four key locations to evaluate the pericardial space, subxiphoid region, hepatorenal recess, and suprapubic region. The subxiphoid region is scanned to assess the pericardial space for fluid, the hepatorenal recess (also known as Morison's pouch) is scanned to detect free fluid between the liver and right kidney, the splenorenal recess is scanned to detect free fluid between the spleen and left kidney, and the suprapubic region is scanned to evaluate the bladder and pelvic organs. The correct placement of the probe is crucial to accurately identify or rule out free intraperitoneal fluid.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it does not specify the correct locations for the FAST examination.
**Option B:** Incorrect because it does not mention the subxiphoid region for pericardial space evaluation.
**Option C:** Incorrect because it does not include the suprapubic region for bladder and pelvic organ evaluation.

**Clinical Pearl / High-Yield Fact**
Remember the mnemonic **"PSA**" to recall the four points of probe placement: **P** ericardial space (subxiphoid region), **S** splenorenal recess, **A** hepatorenal recess (Morison's pouch), and **A** bladder and pelvic organs (suprapubic region).

**Correct Answer: D.