**Core Concept**
The Heimlich manoeuvre is a first-aid technique used to relieve upper airway obstruction caused by a foreign body, such as food or an object, lodging in the trachea. It involves a series of abdominal thrusts to dislodge the object and restore airway patency.

**Why the Correct Answer is Right**
The Heimlich manoeuvre works by increasing intrathoracic pressure, which in turn compresses the lungs and pushes the diaphragm upwards, thereby dislodging the foreign body from the trachea. This technique is effective because it takes advantage of the natural pressure gradient within the thoracic cavity to clear the airway obstruction. The abdominal thrusts, typically performed by the rescuer, help to augment this pressure gradient and facilitate the dislodgement of the foreign body.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the Heimlich manoeuvre is not typically indicated for lower airway obstruction, which may require other interventions such as bronchoscopy or endotracheal intubation.
**Option B:** This option is incorrect because the Heimlich manoeuvre is not a treatment for cardiac arrest, although it may be performed as part of a larger first-aid response in the event of a cardiac arrest.
**Option C:** This option is incorrect because the Heimlich manoeuvre is not a surgical procedure and should not be performed by a surgeon or in a surgical setting.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the Heimlich manoeuvre should only be performed by a bystander or first-responder if the person is conscious and able to cough. In cases where the person is unconscious or unable to cough, other interventions such as back blows or the use of a bag-valve-mask (BVM) device may be more effective.

**Correct Answer: C. Upper airway obstruction**