根据短文内容，选择正确的选项.
One day, Mr. Read and his son Robert were going out for a walk. He put on a pair of shoes together with a pair of different socks, one white and one yellow. As he came out of his house, his sonnoticedthe colors of his father's sock and said, "You have put on two different socks, dad. "
When he heard this, he looked at his socks and found that his son was right. He was happy andsaid to himself（自言自语）. "What a clever son I have got!" Then he said to his son to go back to the house to get another pair of socks for him.
When the son went back to the house, all he could find was one white sock and one yellow sock. Robert then took the socks to his father and said，" It's no use changing!" These socks at home are also different, one yellow and one white. "