**Core Concept**
The cusp–embrasure relationship is a key concept in understanding the occlusal morphology and articulation of teeth. It refers to the contact between the cusp of one tooth and the embrasure of another, which helps in determining the functional relationship between the upper and lower teeth. In a cusp–embrasure relationship, the maxillary first premolar typically articulates with the mandibular second molar, but this can vary depending on the specific tooth morphology and occlusal scheme.

**Why the Correct Answer is Right**
The correct answer is based on the fact that the maxillary first premolar has a specific cusp morphology that allows it to articulate with the mandibular second molar. The maxillary first premolar has a buccal cusp that is larger than its palatal cusp, which enables it to fit into the buccal embrasure of the mandibular second molar. This articulation is facilitated by the conical shape of the buccal cusp of the maxillary first premolar, which matches the shape of the buccal embrasure of the mandibular second molar.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the maxillary first premolar does not typically articulate with the mandibular first molar. The mandibular first molar has a larger occlusal surface and a different cusp morphology that is not compatible with the maxillary first premolar.
* **Option B:** This option is incorrect because the maxillary first premolar does not typically articulate with the mandibular second premolar. The mandibular second premolar has a smaller occlusal surface and a different cusp morphology that is not compatible with the maxillary first premolar.
* **Option C:** This option is incorrect because the maxillary first premolar does not typically articulate with the mandibular first premolar. The mandibular first premolar has a different cusp morphology and a smaller occlusal surface that is not compatible with the maxillary first premolar.

**Clinical Pearl / High-Yield Fact**
In a well-aligned occlusion, the cusp–embrasure relationship between the maxillary first premolar and the mandibular second molar is a key factor in determining the stability and function of the dental arch.

**Correct Answer:** C.