Answer:
Polycyclic aromatic hydrocarbons (from petroleum)
Explanation:
Polycyclic aromatic hydrocarbons (PAH) is a group of compounds which contain more than one aromatic ring. Typically examples include; naphthalene, anthracene, phenanthrene etc.
PAH are present in petroleum products. Almost everyone is regularly exposed to vehicles or other equipments that uses petroleum products as fuel. PAH is usually released from the combustion engine of these equipments and may be inhaled by humans. Thus there is a very high risk of PAH exposure compared to other items listed in the question.
PAHs are known to cause different kinds of cancer and other types of health issues in the body. The most disturbing toxicity of PAH is its carcinogenicity which makes it a very serious potential health risk for humans exposed to it on regular basis.
After crossbreeding, the seeds will be in the form below
Rr, Rr, rr and rr
which is two for each in four possible outcomes bringing the ratio to 1:1
which is equivalent to 1/2
so 1/2 as a percentage is
=1/2*100
=50%
