This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bronchopulmonary Segments, Embryonic veins, Subject name: Anatomy
The proximal pa of the aoa is derived from which of the following? 
Select and explain. 
A. Truncus aeriosus, B. Bulbus cordis, C. Primitive ventricle, D. Primitive atrium
A: Truncus aeriosus
Answer: A: Truncus aeriosus 
Explanation: Proximal pa / arch of aoa is fromed by: 1. Left horn of aoic sac 2. Left 4th phyrangeal arch aery 3. Left dorsal aoa - Neural crest cells migrate to truncus aeriousus and forms AP septum (spiral septum) which divides Truncus into anterior Aoa and posterior Pulmonary trunk. Thus the proximal pa of the aoa is derived from the truncus aeriosus. - From truncus aeriosus develops aoic sac with left and right horns . - Truncus aeriosus forms the outflow tract and blood is pumped by hea into phrangeal arch aeries and dorsal aoa