This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thorax, Subject name: Anatomy
Which of the following does not contribute to the development of diaphragm? 
Select and explain. 
A. Septum transversum, B. Pleuroperitoneal folds, C. Body wall, D. Septum primum
D: Septum primum
Answer: D: Septum primum 
Explanation: Diaphragm develops from the following sources. 1.Septum transversum forms the central tendon. 2.Pleuroperitoneal membranes form the dorsal paired poion. 3. Lateral thoracic wall contributes to the circumferential poion of the diaphragm. 4. Dorsal mesentry of esophagus forms the dorsal unpaired poion. Ref.B D Chaurasia's human anatomy vol.2