This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Special Senses, Subject name: Physiology
[{'content': 'Which of the following best describes the permeability to sodium and potassium in rod cells in response to the light? \nSelect and explain. \nA. Decreased sodium permeability, decreased potassium permeability, B. Decreased sodium permeability, increased potassium permeability, C. Decreased sodium permeability, no change in potassium permeability, D. Increased sodium permeability, decreased potassium permeability', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Activated rhodopsin (metarhodopsin II) closes cGMP-gated sodium channels by lowering levels of cGMP; this action decreases sodium permeability. Potassium permeability is not affected.', 'role': 'assistant'}]