Heart sound which is longer is

Options

A. lub
B. dup
C. both equal
D. sometimes (a) and sometimes (b)

Explanation

To determine which heart sound is longer, we need to analyze the two main heart sounds: "lub" and "dub."

### Step-by-Step Solution:

1. **Identify the Heart Sounds**:
- The two primary heart sounds are referred to as "lub" (S1) and "dub" (S2).
- "Lub" is the first heart sound, while "dub" is the second heart sound.

2. **Understand the Cause of Each Sound**:
- The "lub" sound is produced by the closure of the atrioventricular (AV) valves (the mitral and tricuspid valves).
- The "dub" sound is produced by the closure of the semilunar valves (the aortic and pulmonary valves).

3. **Compare the Duration of Each Sound**:
- The "lub" sound is characterized as a low-pitched sound and is generally longer in duration.
- The "dub" sound is a high-pitched sound and is shorter in duration compared to the "lub" sound.

4. **Conclusion**:
- Since the "lub" sound is longer in duration than the "dub" sound, the answer to the question is that the heart sound which is longer is "lub".

### Final Answer:
The heart sound which is longer is "lub".