Cancers are caused by the accumulation of changes to the DNA. Some of these changes may be inherited but most will be induced by environmental factors such as carcinogens and radiation.
a) Please explain how diverse factors such as hereditary events and environmental agents can both lead to an increased rate of developing cancer?

Some people may have a higher tendency to develop a certain type of cancer   because they carry the gene mutation from their ancestors. For example, in case of women, inheriting a gene mutation in BRCA1 or BRCA2 puts her at a higher risk of developing breast cancer or ovarian cancer.

Environmental agents such as smoking (tobacco), exposure to ultraviolet radiation, certain viruses, to name a few are responsible to the development of cancer in the human body. Overtime, any of these factors can cause irreversible damage to the DNA that could lead to cancer.

Hope that answers the question, have a great day!

geologic time scale (for gradpoint) =)