Recently, China UnionPay did an experiment in a subway station in Beijing--Are you willing to offer a hand to a stranger who needs help? The leading role of the experiment was an old man. With a small bag in one hand and a large case in the other, the old man appeared in a cold winter morning in the bustling  subway station. He was so old that he couldn't carry the heavy case up the stairs. Standing in front of the steps, he looked helpless. Something good happened finally. At 9 o'clock, a kind man showed up, he offered to carry the case for the old man and walked up the stairs with him, at 9:25, another man helped ... Within six hours,the old man walked up the stairs for 25 times,among which he was helped for 23 times. What's more,two ladies tried to help the old man--one in the front and the other in the back. They carried the case up the stairs for him. The most noteworthy thing was that another old man tried to help too. When these kind people were asked why they helped the stranger,they all said " It's just the right thing to do," "I always help people as long as I can" ,or "it's not a big thing, and I just want to help". We often see negative news about fake falling and blackmailing or scheming  and cunning. But this experiment brought sheer warmth into our heart. What do we know about the old man?
He lived a hard and miserable life. He helped to do the experiment. He was too weak to carry the case upstairs. He left after being helped by another old man.
Question: Recently, China UnionPay did an experiment in a subway station in Beijing--Are you willing to offer a hand to a stranger who needs help? The leading role of the experiment was an old man. With a small bag in one hand and a large case in the other, the old man appeared in a cold winter morning in the bustling  subway station. He was so old that he couldn't carry the heavy case up the stairs. Standing in front of the steps, he looked helpless. Something good happened finally. At 9 o'clock, a kind man showed up, he offered to carry the case for the old man and walked up the stairs with him, at 9:25, another man helped ... Within six hours,the old man walked up the stairs for 25 times,among which he was helped for 23 times. What's more,two ladies tried to help the old man--one in the front and the other in the back. They carried the case up the stairs for him. The most noteworthy thing was that another old man tried to help too. When these kind people were asked why they helped the stranger,they all said " It's just the right thing to do," "I always help people as long as I can" ,or "it's not a big thing, and I just want to help". We often see negative news about fake falling and blackmailing or scheming  and cunning. But this experiment brought sheer warmth into our heart. What do we know about the old man?
A. He lived a hard and miserable life.
B. He helped to do the experiment.
C. He was too weak to carry the case upstairs.
D. He left after being helped by another old man.
Answer: