题目选项分析

The army cutworm moth is a critical source of fat for as many as a third of Yellowstone National Park's grizzly bears; overturning rocks to find the insects, consuming up to 40,000 per bear in a single day.

The army cutworm moth is a critical source of fat for as many as a third of Yellowstone National Park's grizzly bears, which overturn rocks to find the insects, consuming as many as 40,000 per bear in a single day.