**Core Concept**
The question is testing the understanding of the anatomy and clinical presentation of pelvic fractures, specifically the association with genitourinary trauma. The patient's symptoms, including blood at the meatus, suggest a possible urethral injury.

**Why the Correct Answer is Right**
The presence of blood at the meatus, in combination with a pelvic fracture, is highly suggestive of a urethral injury, specifically an anterior urethral disruption. This is due to the close proximity of the urethra to the pelvic ring and the increased susceptibility to injury in the setting of a pelvic fracture. The mechanism of injury, involving a direct blow to the perineum, further supports this diagnosis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option might be tempting, as a pelvic fracture can be associated with bladder injury. However, the presence of blood at the meatus is more suggestive of a urethral injury than a bladder injury, which typically presents with hematuria.

**Option B:** This option is incorrect, as a femoral fracture would not typically present with blood at the meatus. While a femoral fracture can be associated with significant trauma, the specific symptom of blood at the meatus is more indicative of a urethral injury.

**Option C:** This option is also incorrect, as a lumbar spine fracture would not typically present with blood at the meatus. While a lumbar spine fracture can be associated with significant trauma, the specific symptom of blood at the meatus is more indicative of a urethral injury.

**Clinical Pearl / High-Yield Fact**
The presence of blood at the meatus in a patient with a pelvic fracture is a classic indication of a urethral injury. This symptom should prompt immediate suspicion of a urethral disruption and prompt evaluation with retrograde urethrography or cystoscopy.

**Correct Answer:**
D. Urethral injury