Final answer:
Environmental risk factors, such as pathogens, radon, air pollution, UV light, and unhealthy lifestyle choices like smoking and poor diet, contribute to increased cancer risk.
Step-by-step explanation:
One line of evidence supporting the idea that cancer is influenced by environmental factors is the presence of environmental risk factors that increase the risk of developing cancer. For example, certain pathogens like hepatitis viruses can increase the risk of liver cancer, while nonpathogenic factors like radon, air pollution, and UV light can increase the risk of lung cancer, bladder cancer, and skin cancers respectively. Lifestyle choices such as smoking, unhealthy diet, and lack of exercise are also important environmental risk factors for cancer.