A carcinogen is BEST described as a _________.

• A. substance that prevents cancer
• B. substance that causes cancer
• C. substance that cures cancer
• D. substance that irritates skin

Answer: (B)

A carcinogen is a substance that increases the risk of developing cancer by damaging DNA or altering the regulation of cell growth, which can lead to uncontrolled cell proliferation over time. That means the item describes cancer-causing potential, not something that prevents cancer, cures it, or merely irritates the skin. Examples include tobacco smoke carcinogens, certain aflatoxins, ultraviolet or ionizing radiation, and asbestos. The other ideas—preventing cancer, curing cancer, or simply causing skin irritation—don’t capture the defined role of a carcinogen, which is specifically about inducing or promoting cancer development.