In which of these vectors the size of the DNA that can be cloned is the smallest?

Plasmids are the self-replicating circular DNA molecules in the bacterial cells. These plasmids are used for the transfer of the desired genes into the other cells and are known as vectors. These plasmids are smaller molecules and help in the cloning of only upto 15 kb of the DNA segment. The other vectors like the BAC, YAC and cosmids can hold 30-3000 kb of the DNA segment. Thus, the correct answer is Plasmid.