A project is struggling because the sponsor continually has to increase funding which may cause the project to get cancelled. This could have been avoided by using:

Quality metrics assess the quality of deliverables but do not manage financial resources or project funding.

Change control is a formal process used to manage all project changes, including those to scope, schedule, and budget. By establishing a defined process for reviewing, approving, or rejecting proposed changes, it prevents uncontrolled financial escalations and ensures that funding adjustments are justified and sustainable, thus avoiding project cancellation due to budget overruns.

A Work Breakdown Structure (WBS) decomposes project work but does not directly manage project funding or changes to it.

Fixed costs are a type of expense that remains constant regardless of activity level, but this concept alone does not provide a mechanism to control funding increases for the project as a whole.