The correct option is
B Vector DNA - Site for tRNA synthesis
Somatic hybridization also called as protoplast fusion, is a type of genetic modification in plants by which two distinct species of plants are fused together to form a new hybrid plant with the characteristics of both, a somatic hybrid.
Micropropagation is the practice of rapidly multiplying stock plant material to produce a large number of progeny plants, using modern plant tissue culture methods.
Callus is an unorganised mass of cells produced in tissue culture.
A cloning vector is a small piece of DNA, taken from a virus, a plasmid, or the cell of a higher organism, that can be stably maintained in an organism, and into which a foreign DNA fragment can be inserted for cloning purposes. It is not a site for t-RNA synthesis.
So, the correct answer is option B.