In a standard ECG which one of the following alphabets is the correct representation of the respective activity of the human heart ?

Options

A. a) S - start of systole
B. b) T - end of diastole
C. c) P - depolarisation of the atria
D. d) R - repolarisastion of ventricles

Explanation

To solve the question regarding the correct representation of the respective activity of the human heart in a standard ECG, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Components of an ECG**:
- An electrocardiogram (ECG) consists of several key components: P wave, QRS complex, and T wave.
- Each of these components represents different electrical activities of the heart.

2. **Identify the P Wave**:
- The P wave represents the depolarization of the atria (auricles). This is the electrical activity that triggers the contraction of the atria.

3. **Identify the QRS Complex**:
- The QRS complex represents the depolarization of the ventricles. This is a crucial phase where the ventricles contract to pump blood out of the heart.

4. **Identify the T Wave**:
- The T wave represents the repolarization of the ventricles. This phase occurs after the contraction of the ventricles and signifies the end of the systole.

5. **Evaluate the Options**:
- Option A: "A represents the start of the systole" - Incorrect, as the QRS complex represents ventricular depolarization which starts systole.
- Option B: "T is the end of diastole" - Incorrect, as the T wave indicates the end of ventricular repolarization, not diastole.
- Option C: "P represents depolarization of atria" - Correct, as the P wave indeed represents atrial depolarization.
- Option D: "R represents depolarization of ventricles" - Incorrect, as the entire QRS complex represents ventricular depolarization, not just R.

6. **Conclusion**:
- The correct answer is Option C: "P represents depolarization of the atria."