The rhythmic expansion and contraction of the heart is called ______.

Options

A. Pulse Rate
B. Heart Beat
C. Pulse
D. Movement

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the term that describes the rhythmic expansion and contraction of the heart.

2. **Identifying Key Terms**: The key terms in the question are "rhythmic," "expansion," and "contraction," which are related to the functioning of the heart.

3. **Defining the Cardiac Cycle**: The rhythmic expansion and contraction of the heart is known as the **Cardiac Cycle**. This cycle includes two main phases:
- **Cardiac Diastole**: This is the phase when the heart relaxes and fills with blood.
- **Cardiac Systole**: This is the phase when the heart contracts and pumps blood out.

4. **Conclusion**: Therefore, the answer to the question is that the rhythmic expansion and contraction of the heart is called the **Cardiac Cycle**.

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