Answer:
I think it's the 2nd option.
The mechanical vector that injects recombinant DNA directly into the nucleus of a host cell is a gene gun. A vector transports pathogens to the susceptible individual without any biologic development . On the other hand, the bacterial plasmid is a biological vector.
Cytosine is one of the maine bases found in DNA and RNA along with adenine guanine and thymine (uracil in RNA) it is pyrimidine deravitive with nytrocyclico arotomic ring and two substitutes attached