Answer:
More than one factor caused the cancer.
Explanation:
Multi factorial disease refers to the type of diseases that is caused by more than one genetic or Environmental factors.
We can see this on Suzanne's situation:
1. We know that Some of her family members have had lung cancer. This means that she is most likely have genetic composition that make her become more likely to get cancers. (first factors)
2. We know that Suzanne was exposed to years of air pollution, which also increase the risk of cancer. (two factors)