**Core Concept**
The question is testing the student's understanding of the neural control of respiration, specifically the role of different types of neurons in regulating the respiratory cycle. **Pneumotaxic centers**, **pneumotaxic neurons**, and **inspiratory neurons** all play critical roles in regulating breathing, but the question is focused on the specific action of forceful expiration.

**Why the Correct Answer is Right**
Forceful expiration is primarily mediated by the **abdominal muscles** and the **internal intercostal muscles**, which are activated by the **phrenic motor neurons**. However, the question is asking about the neural control of forceful expiration, not the muscles themselves. The correct answer is the type of neuron that predominantly fires during forceful expiration. The **abdominal expiratory neurons**, also known as **abdominal inspiratory neurons** or **abdominal expiratory neurons** but more commonly referred to as **abdominal expiratory neurons**, are responsible for the contraction of the abdominal muscles during forceful expiration. These neurons are activated by the **inspiratory neurons** and the **pneumotaxic centers**, which help to regulate the rate and depth of breathing.

**Why Each Wrong Option is Incorrect**
* **Option A:** is not accurate as it does not directly relate to forceful expiration. **Pneumotaxic centers** are involved in regulating the rate of breathing, but they are not the primary neurons responsible for forceful expiration.
* **Option B:** is not correct because **inspiratory neurons** are primarily involved in regulating the inhalation phase of breathing, not forceful expiration.
* **Option D:** is not accurate as it does not directly relate to forceful expiration. **Dorsal respiratory group** neurons are involved in regulating the inspiratory phase of breathing, but they are not the primary neurons responsible for forceful expiration.

**Clinical Pearl / High-Yield Fact**
The abdominal expiratory neurons are responsible for the contraction of the abdominal muscles during forceful expiration, which is essential for activities such as coughing and heavy lifting.

**Correct Answer:** C.