A. During the planning phase, the project manager should have recognized the relationship between the vendor's and project team's tasks and adjusted the schedule for the project team to begin activities two months later.

B. The project manager should have crashed the schedule for the vendor to keep it at the same work pace as the rest of the project team.

C. During the project team's regular status meeting with the vendor, the project team should have informed the vendor that the team was ahead of schedule and to speed up their work.

D. During the project team's regular status meeting with the vendor, the vendor should have informed the project team that it required another two months, and to slow down.