Which of the following contracts should you use for projects that have a degree of uncertainty and require a large investment early in the project?

I would go for option A Cost Reimbursable Contract

Fixed price and lump sum is the same type of contract , with very complete statement of work,

T&M is used when we have uncertainty, but is for a short time period and is used when we want to deal with a matter, very quickly.

Cost reimbursable contract is the best choice when we have a degree of uncertainty, which means we can not define well and clearly the statement of work of the project.

A. is the best answer 

In my opinion - A. Cost reimbursable -   Explanation:  Cost-reimbursable contracts are used when the degree of uncertainty is high and when the project requires a large investment prior to completion of the project.

B. T&M -----------------------

Option A is the best choice.

I would use fixed-price since I do not know what the requirements are and I will not go for lump sum because this might not be fair for any of the parties.

Thank you. I think option A. Cost reimbursable is a good answer.