What is a likely cause of all resource assignments running late now that the project is underway?

The choice indicating that not accounting for hours spent on non-project work is likely the correct answer because it highlights a common issue that can lead to project delays. When team members spend time on tasks that are not directly related to the project, it can significantly impact their availability to focus on project-related activities. This unmonitored time can accumulate, leading to delays across all resource assignments as deadlines are missed due to competing priorities or distractions that were not factored into the initial project schedule.

Understanding this dynamic is crucial in project management since it emphasizes the importance of accurate time tracking and clear distinctions between project and non-project work. Monitoring actual hours worked against planned hours helps to better allocate resources and adjust timelines or tasks promptly to prevent cascading delays throughout the project.