Answer:
• since proposal A and B are mutually exclusive that means we cannot invest in the two proposal at the same time. It's either we invest first on proposal A or B
• Since proposal C is contingent on proposal A being funded, that means we have to achieve proposal A before we can achieve proposal C
• that means for an investment which does not demand extra cost, proposal B is most preferred because it does not depend on any proposal to be achieved before we can start, and it doesn't lead us to extra cost into another investment immediately.
Explanation: proposal A should not be chosing because, since proposal C is dependent on it, that means proposal C will have to play some major role in investment of proposal A, which will lead to more cost.
But proposal B is standing alone and we can still invest in proposal A, after our investment into proposal B has been commissioned.
Proposal C should be the last to invest into because it wholly depends on proposal A.
Hope this answered your question