**Core Concept**
The fourth heart sound (S4) is a low-frequency heart sound that occurs during late diastole, just before the first heart sound (S1). It is associated with atrial contraction and is often heard in conditions with increased atrial pressure or volume.

**Why the Correct Answer is Right**
The fourth heart sound (S4) is produced by the contraction of the atria, which forces blood into the ventricles during late diastole. This sound is often heard in conditions such as hypertension, heart failure, or aortic stenosis, where the atria are under increased pressure or volume. The S4 sound is typically associated with a slow-rising, low-frequency sound that is often felt as a palpable "atrial gallop."

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the S4 sound is not associated with the ventricles. The ventricles do not contract during late diastole, and the S4 sound is not a result of ventricular contraction.
* **Option B:** This option is incorrect because the S3 sound is a high-frequency sound that occurs during early diastole, not late diastole. The S3 sound is often associated with rapid filling of the ventricles.
* **Option C:** This option is incorrect because the S4 sound is not a normal finding in healthy individuals. It is often associated with pathological conditions such as hypertension or heart failure.

**Clinical Pearl / High-Yield Fact**
The S4 sound is often associated with a condition known as "atrial kick," where the atria contract forcefully to fill the ventricles. This can be a sign of underlying cardiac disease, and the presence of an S4 sound should prompt further investigation.

**Correct Answer:** C.