Final answer:
Delayed defibrillation is the action that would be detrimental to a patient in cardiac arrest since prompt defibrillation is necessary for treating ventricular fibrillation that may occur during such an emergency.
Step-by-step explanation:
The question deals with actions taken during a cardiac arrest scenario and asks which of them would be detrimental to a patient. Out of the options given, b) Delayed defibrillation would clearly be detrimental to a patient in cardiac arrest. Defibrillation is critical for treating ventricular fibrillation, a condition where the heart beats in an erratic, uncontrolled manner, which can happen during cardiac arrest. Prompt defibrillation can terminate the arrhythmia and allow the body's natural pacemaker to resume a normal rhythm. The other listed actions, such as initiating chest compressions, administering oxygen, and immediate CPR, are all part of the standard protocol for addressing a cardiac event and would be beneficial to the patient.