阅读下面短文，从短文后各题所给四个选项（A、B、C和D）中，选出可以填入空白处的最佳选项。
It was one of the hottest days of the dry season. It had not rained for almost a month. The crops were dying. Cows had stopped giving milk. If it did not rain soon, we would lose everything. On this day, I witnessed(目睹) a wonder.
I was making lunch when I saw my 6-year-old son, Billy, walking very slowly toward the woods. Minutes later, he came running out again, toward the house. Soon after, I saw him walking toward the woods again. This went on for an hour. Finally, I walked out of the house quietly and followed him.
Billy cupped(使手窝成杯状) both hands in front of him as he walked, careful not to drop the water he carried. Leaves hit his face but he kept walking into the woods. Then I saw an amazing sight. Several large deer stood in front of him. Billy walked right up to them. I saw a tiny baby deer lying on the ground. It was dying of thirst, and it lifted its head with great effort to drink the water in my boy's hands.
When the water was gone, Billy ran back to the house. I followed him to the tap. Billy opened it and a small trickle(细流) came out. He knelt down, letting the drops slowly fill up his "cup".
Now I understood what was going on. The week before, he tried giving water to our horses but I told him not to waste water. Now when he stood up and turned, I was there in front of him. His eyes were filled with tears, "I'm not wasting," he said. I joined him with a small pot of water from the kitchen. I let him walk to the baby deer alone while I stood at the edge of the woods. As tears rolled down my face, they were suddenly joined by other drops... and more drops... as if the sky itself was crying.
