A project manager is working on a project, which needs to be delivered within six months. The project sponsor has made it known that the six months is non-negotiable and additional funding can be provided, if required.
The project is in the fifth month, and testing is ongoing. The project team has identified a major defect that will take up to one month to rectify.
Which of the following is the BEST action for the project manager to take to ensure the project finishes as planned?

A. Obtain additional resources to crash the timelines.
B. Continue the project as is and communicate the imminent one-month delay to the sponsor.
C. Fast-track non-critical-path activities.
D. Deliver the products to meet the timelines and create an additional phase to address issues.