According to the PMBOK® Guide, a Constraint is a limiting factor that affects the execution of a project, program, portfolio, or process. Constraints are often imposed by the organization or by external factors and must be managed by the project manager.

Schedule Constraint: A specific deadline or milestone, such as " The product is needed in 250 days, " is a classic example of a schedule constraint. It limits the project team ' s options regarding duration and resource allocation.

Common Constraints (The Triple Constraint):

Scope: What must be done.

Time/Schedule: Deadlines (like the 250-day requirement).

Cost/Budget: Spending limits.

Other constraints include resources, quality, and risk.

Contrast with Assumptions: While a constraint is a known limitation, an Assumption is a factor that is considered to be true, real, or certain without proof or demonstration.

Analysis of Other Options:

A. Twenty-five percent staff turnover is expected: This is an Assumption or a Risk. It is a factor the team expects to be true, but it is not a predefined limit on how the project must be run.

B. The technology to be used is cutting-edge: This is a Project Characteristic or a Risk. While it influences the project, the " newness " itself isn ' t a restrictive boundary like a budget or a deadline.

C. Project leadership may change...: This is a Risk. It is an uncertain event or condition that, if it occurs, has a positive or negative effect on one or more project objectives.