Identify the incorrect statement:
1. Constipation is caused by decreased motility in the large intestines
2. Diarrhea may result from decreased fluid absorption in the large intestines
3. A high intake of dietary fiber reduces the risk of constipation because it increases distension and motility in the large intestines
4. Bacterial diarrhea results from a bacterial toxin that blocks water channels in the cells of the large intestines