**Core Concept**
The scenario describes a case of traumatic injury to the perineal region, likely resulting from a pelvic fracture and blunt trauma to the lower abdomen. The presenting symptom of blood at the meatus (the external opening of the urethra) suggests a possible urethral injury.

**Why the Correct Answer is Right**
The most likely cause of blood at the meatus in this scenario is a urethral injury, specifically a urethral avulsion or rupture. This is due to the shearing force exerted on the urethra during the pelvic fracture, causing it to tear away from its attachment to the pubic bone. The urethra is particularly susceptible to injury in this region due to its anatomical location and relatively fixed position within the pelvis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because a urethral injury would not typically present with blood at the meatus in the absence of a pelvic fracture. While a urethral injury can occur in isolation, the presence of a pelvic fracture and blood at the meatus strongly suggests a traumatic cause.
**Option B:** This option is incorrect because a penile fracture would not typically present with blood at the meatus, as it would be more likely to present with a visible deformity or hematoma of the penis.
**Option C:** This option is incorrect because a bladder injury would not typically present with blood at the meatus, as it would more likely present with hematuria (blood in the urine).

**Clinical Pearl / High-Yield Fact**
In cases of suspected urethral injury, it is essential to perform a careful digital examination to assess the integrity of the urethra. A high-riding prostate and a decreased or absent urethral caliber are indicative of a urethral injury.

**Correct Answer:** D.