请大家帮忙解答一个语法题目

Alaska regularly deposits some of its profits from the sale of oil into a special fund, with the intention to sustain the state’s economy after the exhaustion of its oil reserves.

A.     fund, with the intention to sustain the stat’s economy after the exhaustion of its oil reserves

B.      fund, the intention of which is to sustain the state’s economy after they have exhausted their oil reserves

C.      fund intended to sustain the state’s economy after oil reserves are exhausted

D.     fund intended to sustain the state’s economy after exhausting its oil reserves

E.      fund that they intend to sustain the state’s  economy after oil reserves are exhausted

我选C

啊。太巧了，我也刚发了个贴问这个！

我在C和D之间犹豫不决。不知道D的after doing有什么错？

A.     fund, with the intention to sustain the stat’s economy after the exhaustion of its oil reserves （表达不如过C直接）

B.      fund, the intention of which is to sustain the state’s economy after they have exhausted their oil reserves （they，their无指代）

C.      fund intended to sustain the state’s economy after oil reserves are exhausted

D.     fund intended to sustain the state’s economy after exhausting its oil reserves （exhausting的主语是谁呢？通过语法判断，应该是fund，但是这个主语不符合逻辑）

E.      fund that they intend to sustain the state’s  economy after oil reserves are exhausted （they无指代）