What part of the body does cancer generally affect?

Cancer can spread anywhere through the body, but it's most likely to spread to lymph nodes, bones, the brain, the liver or the lungs.

Explanation:

See below

Explanation:

Cancer can cause discomfort and loss of function in a specific section of the body by compressing surrounding nerves. Headaches and stroke-like symptoms and indications, such as weakness on one side of the body, are common symptoms and indicators of cancers that damage the brain.

Cancer may spread to any region of the body, although lymph nodes, bones, brain, liver, and lungs are the most commonly affected.

the right option is; decreased genetic variation  

decreased genetic variation describes the effect of this environmental change.

genetic variation is the naturally occurring genetic diversities or differences between organisms of the same species in a population. genetic variation allows the survival and adaptability of a species when they encounter changing environmental conditions. when an endangered species reduces, it loses genetic variation which may not be restored even if the species rebound and will only be recovered through the gradual collection of mutations over many years.