In PMBOK terminology, which statement best distinguishes a constraint from an assumption?

• A. Constraint is a limitation on the project; an assumption is a thing accepted as true for planning purposes without proof.
• B. Constraint is a risk; assumption is a constraint.
• C. Constraint is an assumption; assumption is a limitation.
• D. Constraint is a schedule target; assumption is a budget limit.

Answer: (A)

In planning terms, a constraint is a limitation that bounds what you can do on the project, shaping decisions about scope, schedule, and resources. An assumption is something you treat as true for planning purposes when you don’t have proof, such as believing a supplier will deliver on time or that a certain technology will work as expected. The best statement captures this difference, because it correctly defines both ideas and explains how they influence planning: constraints limit options and drive planning choices, while assumptions fill gaps in information and can become risks if they prove false. For example, a fixed deadline or a fixed budget is a constraint that you must work within, whereas the belief that a key piece of equipment will be available when needed is an assumption you plan around. The other options mix up the concepts—constraints are not risks, an assumption is not a constraint, and treating a schedule target or a budget limit as the other concept doesn’t align with how these terms are used in PMBOK terms.