This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Structure and function of protein, Subject name: Biochemistry
In DNA transfer the vectors used to inse smallest to largest DNA is 
Select and explain. 
A. Cosmids, Plasmids, Bacteriophage, B. Plasmids, Bacteriophage, Cosmids, C. Bacteriophage, Cosmids, Plasmids, D. Cosmids, Bacteriophage, Plasmids
B: Plasmids, Bacteriophage, Cosmids
Answer: B: Plasmids, Bacteriophage, Cosmids 
Explanation: Most general plasmids may be used to clone DNA inse of up to 15 kb in size. Phages can readily accept DNA fragments 10 to 20 kb longCosmids can carry inses of chimeric DNA that are 35 to 50 kb long.Ref: Harper 30th edition pg: 455