Read the following statement (I - IV)
I. The machine that is used to obtain ECG of a patient is called an electrocardiograph .
II. The volume of blood pumped out by each ventricle per cardiac cycle is called the cardiac output .
III. The second heart sound is associated with the opening of both semilunar values .
IV. Hypertension is denoted by the ratio of systolic and diastolic pressure in mm of mercury pressure.
How many statement (s) is/ are correct from the above ?

Options

A. Two
B. Three
C. Four
D. One

Answer

To determine how many statements are correct from the given options, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement I: The machine that is used to obtain ECG of a patient is called an electrocardiograph.**
- This statement is **correct**. The electrocardiograph is indeed the machine used to record the electrical activity of the heart, and the output of this machine is called an electrocardiogram (ECG).

2. **Statement II: The volume of blood pumped out by each ventricle per cardiac cycle is called the cardiac output.**
- This statement is **incorrect**. The volume of blood pumped out by each ventricle per cardiac cycle is known as the **stroke volume**, not cardiac output. Cardiac output is the total volume of blood pumped by the heart per minute, which is calculated as stroke volume multiplied by heart rate.

3. **Statement III: The second heart sound is associated with the opening of both semilunar valves.**
- This statement is **incorrect**. The second heart sound (S2) is actually associated with the **closing** of the semilunar valves (aortic and pulmonary valves), not their opening.

4. **Statement IV: Hypertension is denoted by the ratio of systolic and diastolic pressure in mm of mercury pressure.**
- This statement is **correct**. Hypertension is indeed defined based on the measurements of systolic and diastolic blood pressure, typically expressed in mmHg. A common threshold for hypertension is a systolic pressure above 140 mmHg or diastolic pressure above 90 mmHg.

### Conclusion:
- From the analysis, we find that **two statements (I and IV) are correct**, while statements II and III are incorrect.

### Final Answer:
**The number of correct statements is 2.**

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