All people, ______ they are old or young, rich or poor, rich or poor, have been trying their best to

help those in need since the disaster.

[      ]

A. whatever

B. no matter

C. whether

D. however

四部委联合出台意见加快建立流域上下游（），流域上游承担保护生态环境的责任，流域下游地区对上游地区为改善生态环境付出的努力作出补偿。

A.横向生态保护补偿机制

B.综合协调机制

C.调度配套机制

D.中央统筹机制