I always felt sorry for the people in wheelchairs. Some people, old and weak, cannot get around by themselves. Others seem perfectly healthy, dressed in business suits. But whenever I saw someone in a wheelchair, I only saw a disability, not a person. Then I fainted at Euro Disney due to low blood pressure. This was the first time I had ever fainted, and my parents insisted that I rest for a while after first aid. They said to me, " _ !" I agreed to take it easy, but as I stepped toward the door, I saw my dad pushing a wheelchair in my direction! Feeling the color burn my cheeks, I asked him to wheel that thing right back to where he found it. I could not believe this was happening to me. Wheelchairs were fine for other people but not for me, as my father wheeled me out into the main street, people immediately began to treat me differently. Little kids ran in front of me, forcing my father to stop the wheelchair suddenly. Bitterness set in as I was thrown back and forth. "Stupid kids! They have perfectly good legs. Why can't they watch where they are going?" I thought. People stared down at me, pity in their eyes. Then they would look away, maybe because they thought the sooner they forgot me the better. "I'm just like you!" I wanted to scream." The only difference is you've got legs, and I have wheels." People in wheelchairs are not stupid. They see every look and hear each word. Looking out at the faces, I finally understood: I was once just like them. I treated people in wheelchairs exactly the way they did not want to be treated. I realized it is some of us with two healthy legs who are truly disabled. The experience of the author tells us that  _  .
life is the best teacher people often eat their bitter fruit life is so changeable that nobody can foretell one should not do to others what he would not like others to do to him
Question: I always felt sorry for the people in wheelchairs. Some people, old and weak, cannot get around by themselves. Others seem perfectly healthy, dressed in business suits. But whenever I saw someone in a wheelchair, I only saw a disability, not a person. Then I fainted at Euro Disney due to low blood pressure. This was the first time I had ever fainted, and my parents insisted that I rest for a while after first aid. They said to me, " _ !" I agreed to take it easy, but as I stepped toward the door, I saw my dad pushing a wheelchair in my direction! Feeling the color burn my cheeks, I asked him to wheel that thing right back to where he found it. I could not believe this was happening to me. Wheelchairs were fine for other people but not for me, as my father wheeled me out into the main street, people immediately began to treat me differently. Little kids ran in front of me, forcing my father to stop the wheelchair suddenly. Bitterness set in as I was thrown back and forth. "Stupid kids! They have perfectly good legs. Why can't they watch where they are going?" I thought. People stared down at me, pity in their eyes. Then they would look away, maybe because they thought the sooner they forgot me the better. "I'm just like you!" I wanted to scream." The only difference is you've got legs, and I have wheels." People in wheelchairs are not stupid. They see every look and hear each word. Looking out at the faces, I finally understood: I was once just like them. I treated people in wheelchairs exactly the way they did not want to be treated. I realized it is some of us with two healthy legs who are truly disabled. The experience of the author tells us that  _  .
A. life is the best teacher
B. people often eat their bitter fruit
C. life is so changeable that nobody can foretell
D. one should not do to others what he would not like others to do to him
Answer: