This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: general microbiology, Subject name: Microbiology
[{'content': 'The major constituents in agar are \nSelect and explain. \nA. Fats, B. Aminoacids, C. Polysaccharides, D. Polypeptides', 'role': 'user'}, {'content': "Answer: C \nExplanation: Agar, a polysaccharide extract of a marine alga, is uniquely suitable for microbial cultivation because it is resistant to microbial action and becauseit dissolves at 100degC but does not gel until cooled below 45degC; cells can be suspended in the medium at 45degC and the medium quickly cooled to a gel without harming them.Ref: Jawetz, Melnick, & Adelberg's Medical Microbiology; Twenty-Seventh Edition; Chapter 5; Cultivation of Microorganisms", 'role': 'assistant'}]