Option B (Episome) is correct because the textbook explicitly states that 'Some plasmids can integrate into chromosomes. Such plasmids are called episomes.' This is the defining characteristic of episomes. The other options are incorrect based on the context: Col plasmids produce toxins called 'colicins' which kill other bacteria, R-plasmids provide drug-resistance by encoding enzymes that deactivate antibiotics, and Ti plasmid is not discussed in the provided context. The term 'episome' specifically refers to plasmids that have the ability to integrate into the host chromosome.