Which of the following is a risk factor associated with colorectal cancer?

Long-standing inflammatory bowel disease is a well-established risk factor for colorectal cancer. Conditions such as ulcerative colitis and Crohn's disease lead to chronic inflammation of the intestinal lining. This persistent inflammation can cause changes in the cells of the bowel, promoting dysplasia and potentially leading to cancer over time. The risk of developing colorectal cancer increases significantly with the duration of the disease, especially after 8-10 years of having the condition.

In contrast, while obesity, low-fiber diet, and physical inactivity are also associated with an increased risk of colorectal cancer, they relate to more general lifestyle and dietary factors rather than a specific chronic condition like inflammatory bowel disease. Therefore, the direct connection of long-standing inflammatory bowel disease to the cancer's development makes it the correct choice among the options provided.