This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Toxicology - 1, Subject name: Forensic Medicine
[{'content': 'The toxic substance responsible for floppy baby syndrome is \nSelect and explain. \nA. Lithium, B. Cadmium, C. Antimony, D. Barium', 'role': 'user'}, {'content': 'Answer: A \nExplanation: It is seen in newborn babies breastfed by lithium-ingesting mothers due to disruption of afferent inputs from stretch receptors. Manifesting as hypotonicity, lethargy, and cyanosis (floppy baby syndrome).', 'role': 'assistant'}]