A 30-year-old patient becomes unresponsive after choking.

Comprehensive and Detailed Explanation (Based on NREMT standards):

When a previously choking adult becomes unresponsive, NREMT guidelines require the EMT to immediately begin the cardiac arrest sequence.

Option A (Check for a pulse) is correct because determining pulselessness directs the next intervention.

Option B (Begin chest compressions) is correct because chest compressions are initiated if the patient is pulseless and unresponsive. Compressions may also help dislodge the foreign body.

Option C is incorrect because the airway is checked only after compressions begin and ventilations are attempted.

Option D is incorrect because ventilations are attempted after compressions, with airway checks between cycles.

Option E is inappropriate for an unresponsive adult.

NREMT emphasizes following BLS algorithms precisely for airway obstruction leading to unresponsiveness.