**Core Concept**
The paranasal sinuses are air-filled cavities within the skull that develop and expand throughout childhood and adolescence. The development of paranasal sinuses is crucial for understanding various respiratory and sinus-related disorders.

**Why the Correct Answer is Right**
The paranasal sinuses are primarily present in the form of small rudiments or pneumatic cells at birth, but they are not fully developed. The maxillary sinuses are the only paranasal sinuses that are present at birth, although they are small and not fully developed. The frontal, sphenoid, and ethmoid sinuses develop and expand significantly during childhood and adolescence.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect as the paranasal sinuses are not fully developed at birth.
* **Option B:** This option is incorrect as the maxillary sinuses are the only paranasal sinuses that are present at birth, but not fully developed.
* **Option C:** This option is incorrect as the frontal, sphenoid, and ethmoid sinuses are not fully developed at birth.
* **Option D:** This option is incorrect as the paranasal sinuses are not present in the form of solid bone at birth.

**Clinical Pearl / High-Yield Fact**
The maxillary sinuses are the only paranasal sinuses that are present at birth, and they continue to expand and develop throughout childhood and adolescence.

**Correct Answer: B. The maxillary sinuses are the only paranasal sinuses that are present at birth.**