Microbes found to be very useful in genetic engineering are

Question

$\begin{array}{1 1} (a)\;\text{ E.coli and A.tumefaciens} \\ (b)\;\text{ V.cholarae and tailed bacteriophage} \\ (c)\; \text{ Diplococcus sp and Pseudomonas Sp} \\ (d)\ \text{ Crown gall bacterium and Caenorhabditis elegans.} \end{array}$