This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory chain, Subject name: Biochemistry
[{'content': 'The comparison of the amino acid sequence of Cytochrome C different species shows many variations. Most of these variations are found \nSelect and explain. \nA. Randomly, B. Only in helical regions, C. Only in strand regions, D. Mainly in loop regions', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Reference satyanarayana 4e', 'role': 'assistant'}]