A. Kanamycin: Selectable marker (IV), E. coli (i).
B. Plasmid: Cloning vector (I), Agrobacterium (iii).
C. rDNA: Restrictioin Enzyme (II), Ligase (iv).
D. Vector: Ori (III), Control of copy number (ii). Final Answer:
A-IV-i, B-I-iii, C-II-iv, D-III-ii