Which one of the following microbes transform normal plant and animal cells to cancerous cells respectively?

Question

$\begin{array}{1 1} \text{a. Retroviruses and Rhizobium} \\ \text{b. E.coli and A.tumefaciens} \\ \text{c. A.tumefaciens and Retroviruses} \\ \text{d. A.tumefaciens and A.rhizogenes} \end{array}$