Answer:
quarks can't be broken down into smaller components, making them the smallest things we know of.
Explanation:
Secondhand smoke contains more than 7,000 chemicals. Hundreds are toxic and about 70 can cause cancer. ... Secondhand smoke causes numerous health problems in infants and children, including more frequent and severe asthma attacks, respiratory infections, ear infections, and sudden infant death syndrome (SIDS).
I believe the answer would be stimulants.