While preparing to plan a project, the project manager meets with the key stakeholders to determine the flexibility between the project constraints. Which of the following techniques should the project manager consider to reduce personal bias and increase buy-in?

A. Send the stakeholders a survey about the project constraints to complete anonymously
B. Watch and determine which constraint is most important
C. Compare the constraints two at a time and have the stakeholders vote on importance
D. Look at historical information regarding the flexibility preferences of key stakeholders