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: Radiology
[{'content': 'Diagnostic radiation in a pregnant woman may cause: \nSelect and explain. \nA. High fetal exposure, B. Low birth weight babies, C. Abortion, D. Genetic abnormalities in the fetus', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Fetal exposure during dental X-rays is only about 1 microgray, which is lesser than background radiation. However, maternal radiation dose to thyroid gland from dental radiographs can cause low birth weight infants.', 'role': 'assistant'}]