<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:An 82-year-old male with a history of congestive heart failure presented with new-onset atrial fibrillation. He was initially started on carvedilol, but he now requires an additional agent for rate control. He is started on a medicine and is warned by his physician of the following potential side effects associated with this therapy: nausea, vomiting, confusion, blurry yellow vision, electrolyte abnormalities, and potentially fatal arrhythmia. Which of the following is most likely to increase this patients susceptibility to the toxic effects associated with this medication?? A: Hyponatremia, B: Elevated AST and ALT, C: Hypokalemia, D: Increased GFR with normal creatinine, E: Hyperkalemia,  <response>: This is a clinical reasoning question involving a patient with new-onset atrial fibrillation who requires additional rate control with a medication that can cause side effects like nausea, vomiting, confusion, yellow vision, electrolyte abnormalities and fatal arrhythmia. The question asks which condition would increase susceptibility to the toxic effects of this medication. Based on the side effect profile, the medication is likely digoxin. Digoxin toxicity is more likely with electrolyte abnormalities, especially hypokalemia and hyponatremia. Elevated ASTALT, increased GFR and hyperkalemia would not increase digoxin toxicity risk.C: Hypokalemia 