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 state'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

OA: C

What's wrong with options B and D?