**Core Concept**
The question tests the understanding of occlusal mark reduction, which is a critical aspect of dental restoration evaluation. Occlusal mark reduction refers to the decrease in the height of the occlusal marks on a dental restoration when the restoration comes into contact with the opposing tooth or teeth. This phenomenon is often used to assess the accuracy of the restoration's occlusal surface.

**Why the Correct Answer is Right**
The correct answer is related to the concept of occlusal mark reduction. When a new dental restoration is placed, the marks on the opposing tooth or teeth are typically higher due to the increased occlusal height. After the restoration comes into contact with the opposing tooth or teeth, the marks on the opposing tooth or teeth decrease as the occlusal height is reduced. This reduction in occlusal mark height is a sign of proper occlusal adjustment.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the phenomenon of occlusal mark reduction. A decrease in occlusal mark height is not a sign of excessive occlusal adjustment.

**Option B:** This option is incorrect because it does not accurately describe the phenomenon of occlusal mark reduction. A decrease in occlusal mark height is not a sign of inadequate occlusal adjustment.

**Option D:** This option is incorrect because it does not accurately describe the phenomenon of occlusal mark reduction. A decrease in occlusal mark height is not a sign of over-occlusion.

**Clinical Pearl / High-Yield Fact**
To accurately evaluate occlusal mark reduction, dentists use articulating paper to record the occlusal marks on the restoration and the opposing tooth or teeth. The marks are then evaluated to determine the accuracy of the occlusal surface.

**Correct Answer:** C.