[Verified Answer]: Ella is a 69-year-old woman who presents…

Ella is a 69-year-old woman who presents to her family physician with a 3-month history of persistent cough. She tried taking over the counter cough medicine, but it isn’t helping. Ella works in the kitchen at a fast food restaurant. She is morbidly obese with a BMI of 40 and has smoked a pack of cigarettes daily for over 45 years. Her medical history is significant for rheumatoid arthritis, diagnosed at age 29, and type 2 diabetes. Ella’s blood work reveals elevated levels of the liver enzymes AST and ALT, consistent with heavy alcohol consumption. She admits that she has not followed the recommended diabetic diet, does not exercise, and often skips taking her diabetic medications since they are so expensive. A chest x-ray shows multiple numerous lesions on her lungs and liver. Cancers are caused by environmental-lifestyle behaviors, exposures, and genetic factors. The most important cause of cancer is: