Consider the following statements
A marathon runner is likely to show
1. Reduced heart rate
2. Enlarged heart
3. larger stroke volume
4. Decreased arterial blood pressure
Which of the above statement is/are correct?

Options

A. All of the above
B. 1, 2 and 3
C. 1 and 2
D. 1 alone

Answer

To determine which statements about a marathon runner are correct, let's analyze each statement one by one:

1. **Reduced Heart Rate**:
- Marathon runners typically have a lower resting heart rate due to their high level of cardiovascular fitness. This is because their hearts are more efficient at pumping blood. Therefore, this statement is **correct**.

2. **Enlarged Heart**:
- Endurance training, such as marathon running, can lead to an enlarged heart (specifically, an increase in the size of the heart chambers). This is a physiological adaptation to accommodate a greater volume of blood. Thus, this statement is **correct**.

3. **Larger Stroke Volume**:
- Stroke volume refers to the amount of blood pumped by the heart with each beat. Marathon runners generally have a larger stroke volume due to their enhanced cardiovascular efficiency and the enlarged heart. Hence, this statement is **correct**.

4. **Decreased Arterial Blood Pressure**:
- While trained athletes may have lower resting blood pressure, marathon runners typically experience increased arterial blood pressure during intense exercise. However, the resting blood pressure may not be significantly decreased. Therefore, this statement is **incorrect**.

Now, summarizing the analysis:
- Statements 1, 2, and 3 are correct.
- Statement 4 is incorrect.

Thus, the correct statements about a marathon runner are 1, 2, and 3.

### Final Answer:
The correct statements are 1, 2, and 3.