A Project Is Represented by the Activity Durations (Estimated at 90

A project is represented by the activity durations (estimated at 90% likelihood of completion) and precedence requirements shown in the table.What is the length of the project buffer if this project is managed using critical chain methodology? $$\begin{array} { | l | l | l | l | l | l | } \hline \text { Activity } & \text { Predecessor } & \text { Ieength } & \text { Activity } & \text { Predecesser } & \text { Ieength } \\\hline \text { A } & - - & 20 & \mathrm { D } & \mathrm { B } & 16 \\\hline \mathrm { B } & \text { A } & 20 & \mathrm { E } & \mathrm { C } & 8 \\\hline \mathrm { C } & \text { A } & 10 & \mathrm {~F} & \mathrm { D } , \mathrm { E } & 8 \\\hline\end{array}$$

A) 4.5
B) 11.5
C) 20.5
D) 16