**Core Concept**
The patient is hemodynamically unstable due to blunt abdominal trauma, characterized by tachycardia (elevated pulse rate) and hypotension (low blood pressure). This indicates potential internal bleeding or blood loss leading to decreased circulating blood volume, compromising organ perfusion.

**Why the Correct Answer is Right**
In this scenario, the patient requires immediate fluid resuscitation to restore circulating blood volume and improve organ perfusion. The use of intravenous fluids, such as normal saline or lactated Ringer's solution, helps to increase blood pressure and maintain adequate perfusion of vital organs. This is a crucial step in stabilizing the patient before further diagnostic or therapeutic interventions.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because administering a sedative would not address the underlying cause of the patient's hemodynamic instability and may even further compromise respiratory function.
**Option B:** This option is incorrect because administering a pain reliever would not address the patient's life-threatening condition and may mask symptoms of ongoing bleeding or other complications.
**Option C:** This option is incorrect because performing a diagnostic laparoscopy would not be the immediate next step in managing a hemodynamically unstable patient with suspected internal bleeding.

**Clinical Pearl / High-Yield Fact**
In patients with blunt abdominal trauma and signs of hemodynamic instability, remember the "ABC" rule: Address Airway, Breathing, and Circulation (fluid resuscitation) before proceeding with further diagnostic or therapeutic interventions.

**Correct Answer: C. Perform a focused assessment with sonography for trauma (FAST) to quickly identify internal bleeding or other complications.**