Answer: Project Q
Explanation:
If the company can accept only one project, they should accept Project Q because it has a higher net present value than Project P. This is because a higher Net Present value takes precedence to IRR as it discounts cashflows at the company's cost of capital and is already adjusted for cost.
With the company budget at $50 million, accepting Project Q which costs $48 million means that they will be unable to accept Project P. That is fine because Project Q as earlier mentioned, provides a higher NPV.