**Core Concept**
Blast injury is a complex form of trauma caused by the rapid release of energy, resulting in a high-pressure shockwave that can damage tissues and organs. The primary organs affected by blast injury are those with air-filled spaces or those that are highly compliant.

**Why the Correct Answer is Right**
The organs most susceptible to blast injury are the lungs, ears, and gastrointestinal (GI) tract. The lungs are particularly vulnerable due to their air-filled nature, which can lead to barotrauma and pneumothorax. The ears are susceptible to damage from the shockwave, resulting in hearing loss and tinnitus. The GI tract, including the stomach and intestines, can be injured due to the shockwave's effect on gas-filled spaces, leading to bleeding and perforation.

**Why Each Wrong Option is Incorrect**
* **Option A:** While the brain can be affected by blast injury, it is not the primary organ involved. The brain's injury is often secondary to the initial shockwave.
* **Option B:** The liver and spleen are solid organs that are not typically affected by blast injury.
* **Option C:** The skin can be affected by blast injury, but it is not the primary organ involved.

**Clinical Pearl / High-Yield Fact**
In blast injuries, the GI tract is often referred to as the "surgical abdomen" because of the high likelihood of internal injuries requiring surgical intervention.

**Correct Answer: D. Lungs, ears, and gastrointestinal tract.**