## **Core Concept**
Basic Life Support (BLS) focuses on maintaining the function of vital organs until definitive medical treatment can be administered. The primary goal of BLS is to preserve life by ensuring adequate circulation, oxygenation, and ventilation.

## **Why the Correct Answer is Right**
The correct answer targets organs that BLS directly aims to support. BLS primarily involves **cardiopulmonary resuscitation (CPR)**, which includes chest compressions and rescue breaths. Chest compressions help maintain **cardiac** (heart) function by manually pumping blood through the heart and into the rest of the body. Rescue breaths provide **oxygen** to the **lungs**, which then oxygenate the blood. While BLS indirectly benefits other organs, including the **brain (CNS)**, by ensuring circulation and oxygenation, direct support is specifically aimed at the heart and lungs.

## **Why Each Wrong Option is Incorrect**
- **Option C (Kidney):** While the kidneys are vital and benefit indirectly from BLS through improved circulation, they are not directly supported by the interventions used in BLS.
- **Option D (Skeletal muscle):** Skeletal muscles receive oxygen and nutrients through the circulatory system and are indirectly supported, but BLS does not directly target them.
- **Option E (Brain / CNS):** Though crucial and indirectly supported through ensuring adequate circulation and oxygenation, BLS does not directly provide support specifically to the brain.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is the **"ABC"** approach in BLS and ACLS (Advanced Cardiovascular Life Support): **Airway, Breathing, and Circulation**. This sequence emphasizes the importance of securing the airway, ensuring breathing (lungs), and maintaining circulation (heart) to preserve life.

## **Correct Answer:** D. a, b, e