XYZ company undertakes a project that lasts $12$ months. The work of the first six months involves an R&D that is well$-$defined and can be estimated to be level $5$ of the Work Breakdown Structure $($WBS$).$ However, the efforts of the last six months of the project are based on the outcome of the first six months. Sam, as the project manager, has been provided with an experienced estimating group. However, this group has no previous history or experience concerning some deliverables. As a result, the group cannot prepare work packages due to the absence of a clear understanding of the time and cost of the work, which can be estimated at WBS level $2$ only. Sam considers this a high$-$risk project.

a$.$ Instruct Sam to apply the $$moving window$$ approach to minimise the risk and complete the project by explaining parts A$,$ B$,$ and C of the illustration below$\backslash$table$[[$MONTHS AFTER GO$-$AHEAD$],[,1,2,3,4,5,6,7,8,9,10,11,12],[($A$),$WBS LEVEL $5,$WBS LEVEL $2],[($B$),,$WBS LEVEL $5,$WBS LEVEL $2],[($C$),,,$WBS LEVEL $5,$WBS LEVEL $2]]$b$.$ Discuss the level of risk of the project if the length of the $$moving window$$ is shortened or lengthened? c$.$ Explain the potential estimation pitfalls that could lead to increased risks of applying the $$moving window$$ method.