Tar's Carcinogenic Pathway in Lungs

Steps:

• Identify tar as a source of carcinogens that damage lung cell DNA.
• Trace the sequence: carcinogens bind to DNA, causing mutations.
• Link mutations to uncontrolled cell division, leading to cancer.
• Compare choices to select the one matching this logical flow.

Why A is correct:

• Carcinogens in tar alter DNA structure, inducing mutations that disrupt cell cycle control and trigger uncontrolled division, per the definition of carcinogenesis.

Why the others are wrong:

• B: Focuses on mucus hypersecretion and phagocyte response, which relates to irritation, not DNA damage.
• C: Describes a disorganized infection-inflammation cycle, ignoring cancer development.
• D: Presents an illogical mix of mutation and inflammation without clear causation.

Final answer: A