**Core Concept**
The patient's presentation of abdominal injury, peritonitis, and shock indicates a severe intra-abdominal infection, which requires immediate surgical intervention to control the source of sepsis and restore hemodynamic stability.

**Why the Correct Answer is Right**
The correct answer is **C. Immediate laparotomy**. This is because the patient's condition has progressed to a stage where non-operative management is no longer feasible, and surgical intervention is necessary to control the source of sepsis, repair any intra-abdominal injuries, and restore hemodynamic stability. The presence of peritonitis and shock indicates a high likelihood of intra-abdominal organ injury or perforation, which requires prompt surgical intervention.

**Why Each Wrong Option is Incorrect**

* **Option A:** Administering antibiotics alone is not sufficient in this scenario, as the patient's condition has progressed beyond the point where non-operative management can be effective.
* **Option B:** The patient's condition requires immediate surgical intervention, rather than further diagnostic tests or imaging studies.
* **Option D:** While fluid resuscitation is an essential part of shock management, it is not the next line of management in this scenario, where the source of sepsis needs to be controlled through surgical intervention.

**Clinical Pearl / High-Yield Fact**
In patients with abdominal trauma and signs of peritonitis, a high index of suspicion for intra-abdominal organ injury or perforation should be maintained, and prompt surgical intervention should be considered, as delay in treatment can lead to increased morbidity and mortality.

**Correct Answer: C. Immediate laparotomy**