**Core Concept**
Class I cavity preparation is a type of dental cavity preparation that involves one surface of a tooth, typically a mesial or distal surface. This type of preparation is often used for occlusal restorations in the primary teeth or for small lesions in the permanent teeth.

**Why the Correct Answer is Right**
Class I cavity preparations do not include preparations that involve two or more surfaces of a tooth, such as Class II or Class V preparations. These preparations are more complex and require additional removal of tooth structure to accommodate the restoration. In contrast, Class I preparations are relatively simple and involve only one surface of the tooth.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Class I cavity preparations are indeed used for occlusal restorations in the primary teeth, which is a correct application of this classification.
**Option B:** This option is incorrect because Class I cavity preparations do involve one surface of a tooth, making it a correct example of this classification.
**Option C:** This option is incorrect because while Class I cavity preparations may be used for small lesions in the permanent teeth, this is a correct application of this classification.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the classification of dental cavity preparations is based on the number of surfaces involved, with Class I being the simplest and most straightforward.

**Correct Answer:** D.