While creating the project charter, a key stakeholder does not offer any input. The project manager repeatedly asks the stakeholder to provide the necessary input to complete the high-level requirements. Despite the project manager’s efforts，the situation does not improve. What should the project manager do next？
A、Remove the stakeholder from the stakeholder list.
B、Assume the requirements together with the project team.
C、Add the missing input as a risk to the high-level risk description.
D、Escalate the issue to the project sponsor.