Which of the following is a major risk factor for developing liver cancer?

The development of liver cancer is significantly associated with viral infections, particularly hepatitis B and C. These viruses can lead to chronic liver inflammation, liver cirrhosis, and ultimately increase the risk of liver cancer. Infection with either of these viruses is a major risk factor because they are known to cause changes in liver cells over time, contributing to malignancies.

In contrast, excessive sun exposure, while it can lead to skin cancers, does not have a direct link to liver cancer. Smoking is a known risk factor for various cancers, including lung and possibly other types. However, its direct association with liver cancer is not as prominent as that of viral infections. High levels of physical activity tend to benefit overall health and are generally associated with a lower risk of numerous chronic diseases, which would further reduce the risk rather than increase it. Therefore, the connection between hepatitis B/C and liver cancer is well-documented, making it the correct indication of a major risk factor for developing liver cancer.