Explain how environmental agents such as chemicals and radiation cause cancer.

Chemical (mutagens) usually either mimic the structure of nucleotides and are inserted in DNA or either cause chemical changes  (such as alkylation) in nucleotides hence causing mismatching during replication. Radiation, on the other hand, (due to its high energy) causes double-strand breaks in DNA causing an increased likelihood of mutations during the repair of the DNA by cell mechanisms.

d. groundwater flows through the subsoil and deposits minerals.