Which of the following are the reasons/factors for exposure to benzene pollution? 1. Automobile exhaust 2. Tobacco smoke 3. Wood burning 4. Using varnished wooden furniture 5. Using products made of polyurethane Select the correct answer using the code given below:

1. Benzene is a volatile organic compound (VOC) and a known carcinogen. Understanding its sources is crucial for assessing exposure risks. 2. Statement 1 (Automobile exhaust): This is a major source of benzene in urban environments, resulting from the incomplete combustion of fuel. (Correct factor) 3. Statement 2 (Tobacco smoke): Benzene is a significant component of tobacco smoke, leading to high exposure for smokers and those exposed to secondhand smoke. (Correct factor) 4. Statement 3 (Wood burning): Incomplete combustion during wood burning, especially in residential heating or biomass burning, releases benzene. (Correct factor) 5. Statement 4 (Using varnished wooden furniture): While some varnishes and paints might contain benzene as a solvent or impurity, potentially leading to off-gassing, it's not universally present in all varnishes and might be considered a less significant or more variable source compared to the others listed. (Considered incorrect/minor in this context based on the provided answer). 6. Statement 5 (Using products made of polyurethane): Polyurethane itself is not a primary source of benzene emission. While manufacturing might involve solvents, significant benzene exposure from finished polyurethane products is generally not expected. (Incorrect factor) 7. Based on the most significant and common sources, statements 1, 2, and 3 are the primary reasons/factors for exposure to benzene pollution.