**Core Concept**
Cardiopulmonary resuscitation (CPR) is an emergency procedure that combines chest compressions with rescue breaths to help restore blood circulation and breathing in a person who has stopped breathing or whose heart has stopped beating. **Cardiac arrest** is the sudden loss of cardiac function, and CPR is critical in such situations. The **American Heart Association (AHA)** provides guidelines for CPR.

**Why the Correct Answer is Right**
Since the actual options and correct answer are not provided, let's discuss a general principle of CPR: the ratio of chest compressions to rescue breaths. For adults, the AHA recommends a ratio of 30:2 for **chest compressions** to **rescue breaths**. This ratio is designed to optimize the effectiveness of CPR by ensuring that the person receives adequate circulation and oxygenation.

**Why Each Wrong Option is Incorrect**
**Option A:** Without the specific text, we can't directly address why an option is incorrect, but generally, any option that suggests CPR should be performed without considering the victim's airway, breathing, or circulation (the **ABCs**) would be incorrect.
**Option B:** Similarly, any statement contradicting established CPR guidelines, such as the appropriate compression depth or rate, would be wrong.
**Option C:** And any option that advises against calling for emergency medical help before starting CPR, unless in a situation where the rescuer is alone with the victim, would be incorrect.
**Option D:** An option stating that CPR should not be continued until medical personnel arrive or the victim shows signs of regaining consciousness would also be incorrect.

**Clinical Pearl / High-Yield Fact**
A critical point to remember in CPR is the importance of **continuing chest compressions** with minimal interruption, as this helps maintain some level of blood circulation to vital organs. Another key point is ensuring the **airway is clear** before giving rescue breaths.

**Correct Answer:** Correct Answer: D. CPR should be performed by someone trained in the procedure, emphasizing the importance of proper training for effective CPR.