**Core Concept**
The growth and development of oral structures, including teeth and jawbones, is a complex process influenced by both genetic and environmental factors. Hereditary factors determine the overall shape and size of the jaw, while environmental factors play a crucial role in the timing and rate of growth. The interplay between these factors is essential for normal oral development.

**Why the Correct Answer is Right**
The correct answer, "Hereditary-influenced by environmental factor," accurately reflects the current understanding of oral growth and development. Hereditary factors, such as genetic predisposition, determine the overall shape and size of the jaw, while environmental factors, such as nutrition, hormones, and mechanical forces, influence the timing and rate of growth. For example, the growth of the mandible is influenced by both genetic factors, such as the shape and size of the jaw, and environmental factors, such as the force of chewing and the presence of teeth.

**Why Each Wrong Option is Incorrect**
**Option A:** Hereditary alone is an oversimplification of the process, as environmental factors also play a crucial role in oral growth and development.

**Option B:** Environmental factors alone are insufficient to explain the growth and development of oral structures, as hereditary factors provide the foundation for normal growth.

**Option D:** None of the above is incorrect, as option C provides a more accurate explanation of the complex interplay between hereditary and environmental factors.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the growth and development of oral structures are influenced by both genetic and environmental factors, and that a disturbance in either factor can lead to abnormalities in oral growth and development.

**✓ Correct Answer: C. Hereditary-influenced by environmental factor**