## Core Concept
The question tests understanding of cell cycle specificity of anticancer drugs. Cell cycle-specific drugs act on specific phases of the cell cycle (G1, S, G2, or M), whereas cell cycle-nonspecific drugs can act on cells regardless of their phase.

## Why the Correct Answer is Right
Bleomycin (Option C) is a chemotherapeutic agent that works by inducing DNA strand breaks, thereby inhibiting DNA synthesis and cell division. It is most effective during the G2 phase and, to some extent, the M phase of the cell cycle, making it a cell cycle-specific agent. This mechanism involves the generation of free radicals that cleave DNA.

## Why Each Wrong Option is Incorrect
- **Option A:** Cyclophosphamide is an alkylating agent that works by cross-linking DNA strands, which ultimately leads to cell death. This action is not limited to a specific phase of the cell cycle, making it cell cycle-nonspecific.
- **Option B:** Chlorambucil is another alkylating agent similar to cyclophosphamide. It also acts by cross-linking DNA and is not specific to any phase of the cell cycle, making it cell cycle-nonspecific.
- **Option D:** Melphalan is an alkylating agent as well, with a mechanism similar to cyclophosphamide and chlorambucil. It is not specific to any cell cycle phase.

## Clinical Pearl / High-Yield Fact
A key point to remember is that cell cycle-specific drugs are generally more effective against rapidly dividing cells (like cancer cells) but may have different toxicity profiles compared to cell cycle-nonspecific drugs. Bleomycin's use is notable for its efficacy in treating testicular cancer and certain types of lymphoma.

## Correct Answer Line
**Correct Answer: C. Bleomycin.**