Step 1: Concept
Cancer chemotherapeutic agents are classified based on their chemical structures, molecular targets, and mechanisms of action.
Step 2: Meaning
* Antimetabolites masquerade as normal nucleotides.
* Alkylating agents or cross-linkers physically damage DNA.
* Targeted therapies specifically block malfunctioning cellular signaling pathways or proteins.
Step 3: Analysis
* 6-mercaptopurine (A) acts as an antimetabolite that blocks purine nucleotide synthesis by mimicking normal purines $\rightarrow$ (A-IV).
* Mitomycin (B) is a potent antitumor antibiotic isolated from Streptomyces species that acts as a DNA cross-linker $\rightarrow$ (B-III).
* Cisplatin (C) is a platinum-based coordination complex that binds tightly to DNA to form intra-strand cross-links $\rightarrow$ (C-II).
* Imatinib (D) is a targeted small-molecule inhibitor designed to block tyrosine kinase proteins like BCR-ABL, which often shares structural classification with targeted biological pathways $\rightarrow$ (D-I).
Step 4: Conclusion
The resulting unified configuration is A-IV, B-III, C-II, D-I, matching option B.
Final Answer: (B)