How many toxic or carcinogenic compounds have been found in second-hand smoke?

1. Second-hand smoke combines sidestream smoke with the mainstream smoke exhaled by the smoker. 2. At least 250 of its compounds are known to be toxic, carcinogenic, or both. 3. So the first option is correct. 4. The figure of at least 40 belongs to a different claim, namely the chemicals identified in sidestream smoke that harm health, which is the trap in the fourth option. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 22 "The Respiratory System", section 22.2 The Lungs_