A chimeric DNA is formed by

Chimaeric DNA basically means DNA which is formed by DNA fragments from different organisms. It is also called recombinant DNA. The process of making recombinant DNA or chimaeric DNA is called recombinant DNA technology.

The steps in making chimaeric DNA involve isolating DNA, digestion of DNA with restriction enzymes, joining of DNA fragments, inserting the DNA into host cells and finally screening and selection of the transformed cells. 

Since, a plasmid is a self replicating small circular DNA molecule, it is used as a vector for cloning DNA. The plasmid is ligated with a DNA fragment after digestion with restriction endonucleases and transformed into host cells.

Hence, a chimaeric DNA is formed by joining c-DNA or complementary DNA with plasmid.

So, the correct answer is 'Joining c-DNA with plasmid'.