Which of the following is a carcinogen?

• A. Water.
• B. Benzene.
• C. Salt.
• D. Oxygen.

Answer: (B)

Carcinogens are substances that can cause cancer by damaging DNA or promoting abnormal cell growth. Benzene is a well-established carcinogen. When it enters the body, it is metabolized into reactive compounds that can damage bone marrow cells and disrupt normal blood cell production, increasing the risk of leukemia and other cancers. The risk rises with greater or longer exposure, which is why controlling inhalation and skin contact through ventilation, monitoring, and protective measures is essential in environments where benzene is present. The other substances listed do not act as carcinogens under normal conditions: water is essential for life, salt is a common dietary compound, and oxygen supports cellular respiration; none are considered cancer-causing agents in typical hazard recognition.