Using the key, put the phrases in the correct order to form a plasmid-carrying recombinant DNA.
Key:
1. use restriction enzymes
2. use DNA ligase
3. remove plasmid from parent bacterium
4. introduce plasmid into new host bacterium
$\begin{array}{ll}{\text { a. } 1,2,3,4} & {\text { c. } 3,1,2,4} \\ {\text { b. } 4,3,2,1} & {\text { d. } 2,3,1,4}\end{array}$