[A] : The record of electric potential that is ini- tiated in the cardiac muscle is known as Electrocardiograph .
[R]: This is valuable for preliminary studies of heart muscles.

Options

A. If both A and R are true and R is the correct explanation of A
B. If both A and R are true but R is not the correct explanation of A
C. If A is true and R is false
D. If both A and R are false

Answer

**Step-by-Step Solution:**

1. **Understanding the Assertion**: The assertion states that "the record of electric potential that is initiated in the cardiac muscle is known as electrocardiograph." We need to analyze whether this statement is true or false.

2. **Clarifying Terms**: The term "electrocardiograph" refers to the machine used to record the electrical activity of the heart, not the record itself. The actual record produced by this machine is called an "electrocardiogram" (ECG). Therefore, the assertion is incorrect.

3. **Understanding the Reason**: The reason provided states, "this is valuable for preliminary studies of heart muscles." We need to determine if this statement is true or false.

4. **Analyzing the Reason**: While the electrocardiogram (the record) is indeed valuable for studying the electrical activity of the heart, it does not specifically focus on the heart muscles themselves. Instead, it provides insights into the overall heart function and rhythm. Thus, this reason is also incorrect.

5. **Conclusion**: Since both the assertion and the reason are false, the correct answer is that both the assertion and reason are false.

**Final Answer**: The correct option is the fourth one: both assertion and reason are false.

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