Ranger: Higher than normal temperatures are to blame for the decline in the Montana wolverine population over the past five years. Yet clearly, trappers have also played an important role in this decline. In the past five years, the number of Montana trappers and hunters claiming their capture or kill of wolverine has risen sharply. Wolverines, they claim, are particularly fierce and dangerous animals that eat about anything, raid trap-lines, steal food from cabins, and ruin remaining food and belongings with musk and urine.
In the ranger's argument, the boldface portion plays which of the following roles?