**Core Concept**
The maxillary ridge resorption is a common post-extraction phenomenon where the alveolar bone and surrounding tissue undergo changes, leading to a decrease in the overall height and volume of the maxilla. This process is influenced by various factors including age, sex, and the presence of dentition.

**Why the Correct Answer is Right**
The direction of resorption of the maxillary ridge is primarily posterior and superior. This is due to the natural process of bone remodeling, where the body's osteoclasts break down bone tissue, releasing calcium and phosphorus into the bloodstream. In the maxilla, the posterior and superior aspects are more susceptible to resorption due to the thinning of the cortical bone and the presence of a relatively lower density of osteoblasts, which are responsible for bone formation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as the maxillary ridge resorption is not primarily directed anteriorly. The anterior aspect of the maxilla is relatively more stable due to the presence of thicker cortical bone and a higher density of osteoblasts.

**Option B:** This option is incorrect as the maxillary ridge resorption is not primarily directed inferiorly. The inferior aspect of the maxilla is relatively more stable due to the presence of a thicker cortical bone and a lower density of osteoclasts.

**Option D:** This option is incorrect as the maxillary ridge resorption is not primarily directed medially. The medial aspect of the maxilla is relatively more stable due to the presence of a thicker cortical bone and a lower density of osteoclasts.

**Clinical Pearl / High-Yield Fact**
It is essential for dental professionals to understand the direction of resorption of the maxillary ridge to provide accurate treatment plans and prosthetic restorations. A thorough knowledge of the maxillary ridge resorption can help in preventing complications and ensuring the long-term success of dental implants.

**Correct Answer: C. Posterior and superior.**