**Core Concept**
A balanced occlusion is a dental occlusion where the forces on the teeth are evenly distributed, allowing for proper chewing and tooth wear. Incisal guidance refers to the relationship between the upper and lower incisors during closure of the jaws.

**Why the Correct Answer is Right**
When incisal guidance is increased in a balanced occlusion, the upper incisors are positioned further forward, which results in a more pronounced overbite. This can lead to increased anterior tooth wear and potential problems with the temporomandibular joint (TMJ). The increased overbite can also cause the occlusal plane to tilt posteriorly, leading to a more vertical occlusal scheme.

**Why Each Wrong Option is Incorrect**
**Option A:** Increasing incisal guidance would not result in a more open bite, as the upper incisors are positioned further forward, not more posteriorly.
**Option B:** The relationship between the upper and lower molars is not directly affected by incisal guidance, so this option is not relevant.
**Option C:** Increasing incisal guidance does not lead to a more underbite, as the upper incisors are positioned further forward, not more posteriorly.

**Clinical Pearl / High-Yield Fact**
A key aspect of balanced occlusion is the concept of "guidance" - the way the teeth interact during jaw closure. Understanding incisal guidance and its effects on the occlusion is crucial for diagnosing and treating dental malocclusions.

**Correct Answer: A. Increased overbite.**