All team members need to be included in determining time and effort estimates for which of the following reasons?Time and effort required is primarily dependent upon team members' expertise.The team members need to know these estimates to hire contractors.The team members need to know these estimates to delegate tasks.Time and effort required is primarily dependent upon the project manager's expectations.

All team members need to be included in determining time and effort estimates for the following reasons:

1. Time and effort required is primarily dependent upon team members' expertise: Each team member has a unique set of skills and expertise. They are the best judge of how much time and effort they would need to complete their part of the project. Their input is crucial in creating an accurate estimate.

2. The team members need to know these estimates to delegate tasks: Knowing the time and effort estimates can help team members delegate tasks efficiently. They can assign tasks based on the estimated time and effort, ensuring that the workload is evenly distributed and the project can be completed within the stipulated time.

The other two options are not as relevant. Hiring contractors is not directly related to time and effort estimates of the team members. Also, while the project manager's expectations are important, they should not be the primary basis for determining time and effort required. It should be based on the team members' expertise and the actual work that needs to be done.