Please answer the following question: Read the following article and select the best answer. Article: One day, a farmer was walking along a road with his son Thomas. The father said. "Look! There's a horseshoe. Pick it up and put it in your bag." Thomas said, "It isn't worth the trouble." His father said nothing but picked it up himself. When they got to a nearby town, they had a rest. There the farmer sold the horseshoe and with the pennies he bought some grapes. It was very hot, and there wasn't a house or a tree where they could have a rest. Thomas felt too thirsty to walk on. At this time. his father dropped a grape on the ground and Thomas picked it up quickly and ate it. After a while. his father dropped another grape and once again. his son picked it up and put it in his mouth. And so they went on. The old farmer dropped the grapes and the son picked them up. When Thomas had eaten up all the grapes, his father said to him. "My dear son, if you had bent down early to pick up that horseshoe. It would not have been necessary for you to bend so many times for the grapes, always remember the lesson : A person who does not worry about the little things will find that he can not do the great things." Question: Thomas picked up the grapes and ate them because _ . - his father wanted him to eat them - he liked them - he was thirsty - he wanted to sell them
A:
he was thirsty