All people they are old or young rich or poor have been trying their best to help those in

问题补充：

All people,they are old or young，rich or poor，have been trying their best to help those in need since the disaster

A even if B whether C no matterD however

答案：

解析：考查固定措配whether……or……的用法，句意：自从那次灾难以后，所有的人，不论老人还是年轻人、富人还是穷人，都在努力帮助那些需要帮助的人。