阅读下列短文，从每小题的三个选项中选出最佳选项。

    It's summer and it's hot. There's a wildfire (野火) on the hillside (山坡). Bushes (灌木) and trees are burning. Fire engines (消防车) can't help. There are no roads near this fire.

    The firefighting helicopter (消防直升机) is coming to help. It carries a big bucket (桶).

    The pilot flies the helicopter to a lake. He drops the bucket into the lake and it fills (装满) with water. Then the pilot flies to the fire. He drops the water onto the fire. He goes back to the lake and gets more water. He flies from the lake to the hillside again and again.

    Finally, the pilot puts out the wildfire. He does a very important job.