**Core Concept**
The classification of maxillary atrophy proposed by Cawood and Howell is a widely used system to categorize the extent of bone resorption in edentulous patients. This system helps in predicting the success of dental implant placement and guiding surgical planning.

**Why the Correct Answer is Right**
The Cawood and Howell classification system divides maxillary atrophy into four classes, based on the degree of bone resorption. Class I is characterized by a well-preserved maxilla with minimal bone loss, while Class II shows a slight depression in the alveolar ridge. Class III features a more pronounced depression, often with a cup-shaped surface, as described in the question. This classification is essential for clinicians to determine the most suitable treatment approach for patients with varying degrees of maxillary atrophy.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not mentioned in the Cawood and Howell classification system, making it an incorrect choice.
**Option B:** This option might be a characteristic of another classification system, but it is not specific to the Cawood and Howell classification.
**Option D:** This option is also not a part of the Cawood and Howell classification system, indicating that it is not the correct answer.

**Clinical Pearl / High-Yield Fact**
When assessing maxillary atrophy, clinicians should be aware that the Cawood and Howell classification system is a useful tool for predicting the success of dental implant placement. However, it is essential to consider other factors, such as patient anatomy and medical history, when making treatment decisions.

**Correct Answer: C. Class III**