This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Embryology 1, Subject name: Anatomy
[{'content': 'The intervillous space of the placenta contains \nSelect and explain. \nA. Maternal blood, B. Fetal blood, C. Maternal and fetal blood, D. Amniotic fluid', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The intervillous space contains only maternal blood as the spiral aeries of the endometrium penetrate the outer cytotrophoblast shell.', 'role': 'assistant'}]