Which statement correctly describes cancer formation? Cancer is formed when people participate in risky behaviors.
Cancer is formed when cancer genes are inherited.
Cancer is formed when there are mutations in a number of genes.
Cancer is formed when people are exposed to cancer-causing agents.

Cancer is formed when there are mutations in a number of genes.

Explanation:

Malignant tumors are gene diseases which do not mean that cancer is necessarily an inherited disease (only in 5-10% of cases the cancer is inherited) because the vast majority of other tumors are the result of somatic, ie secondary, mutations that lead to malignant transformation.

Only 2% of human diseases are monogenic (caused by a change in one gene). The remaining 98% of the disease is either polygenic (caused by a change in several genes at the same time) or epigenetic (caused by non-genetic or post-genetic disorders of cellular molecules).

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.

youre right there are