The following table of probabilistic time estimates $($in weeks$)$ and activity predecessors are provided for a project.

$\backslash$table$[[$Activity$,\backslash$table$[[$optimistic$],[$time$]],\backslash$table$[[$most likely$],[$time$]],\backslash$table$[[$pessimistic$],[$time$]],\backslash$table$[[$Activity$],[$Predecessor$]]],[$A$,3,5,7,-],[$B$,4,8,10,$A$],[$C$,2,3,5,$A$],[$D$,6,9,12,$B$,$ C$],[$E$,5,9,15,$D$]]$

Table $1$

Reference: Ref $1$

Using Table $1,$ the variance of the project's total completion time is

A$.3\mathrm{.}752$

B$.5\mathrm{.}222.$

C$.4\mathrm{.}872$

D$.5\mathrm{.}472.$