As a project manager on a construction project, you learn that labor negotiations at one of your supplier's factories could temporarily interrupt future delivery of materials to your project. To minimize the impact of this circumstance, you order extra materials now, to carry your project through any future interruptions. Which flexible planning strategy did you use to deal with this situation?

Calculating "float" in your schedule.

Assessing external constraints

Planning for risks and challenges

Enabling decision$-$making