This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Pacemaker regulating the rate of respiration: 
Select and explain. 
A. Pneumotaxic center, B. Dorsal group of nucleus, C. Apneustic center, D. Pre Botzinger complex
D: Pre Botzinger complex
Answer: D: Pre Botzinger complex 
Explanation: Pacemaker of respiration is Pre-Botzinger complex of neurons, which is a part of Ventral Respiratory Group(VRG) in medulla.