**Core Concept**
Tension pneumothorax is a life-threatening condition characterized by the accumulation of air under pressure in the pleural space, leading to compression of the lung and mediastinal structures. It requires immediate recognition and intervention to prevent further complications and mortality.

**Why the Correct Answer is Right**
The first line of management in tension pneumothorax involves the insertion of a large-bore needle or cannula into the second intercostal space in the mid-clavicular line on the affected side. This allows for the release of trapped air and equalization of pressure in the pleural space. The needle or cannula is typically connected to a Heimlich valve or a three-way stopcock to prevent further air entry. This initial intervention is crucial in stabilizing the patient and preventing further deterioration.

**Why Each Wrong Option is Incorrect**
* **Option A:** Needle decompression is not the first line of management in tension pneumothorax. However, it may be considered as a temporary measure until a chest drain can be inserted.
* **Option B:** Intercostal tube thoracostomy is the definitive management of tension pneumothorax, but it requires more time and resources to set up compared to needle decompression.
* **Option D:** Administration of oxygen and cardiac monitoring are supportive measures, but they do not address the underlying cause of the tension pneumothorax.

**Clinical Pearl / High-Yield Fact**
In the management of tension pneumothorax, needle decompression should be performed in the second intercostal space in the mid-clavicular line, taking care to avoid the internal mammary artery and vein.

**Correct Answer: C. Insertion of a large-bore needle or cannula into the second intercostal space in the mid-clavicular line on the affected side.**