题目选项分析

The arctic fox was once the most common fox on the Northern Island. Recently, the number of red fox on the island surpassed, for the first time, that of the arctic fox. Nonetheless, both foxes eat the same prey and share the same environment.

Which of the following, if true, could best account for the decrease in arctic fox relative to the red fox?

【选项】The polar bear, the arctic fox's primary predator, has become increasingly less common on the island.