Consider the Following Work Breakdown Structure What Is the Estimated Slack Time for Activity A?
A)

Consider the following work breakdown structure: $$\begin{array}{l}\begin{array} { c c c c c } &&&\text { Time Estimates (days) }\\\text { Activity } & \text { Precedes } & \text { Optimistic } & \text { Most Likely } & \text { Pessimistic } \\\hline \text { Start } & \text { A, B, C } & - & - & - \\\text { A } & \text { D } & 38 & 50 & 62 \\\text { B } & \text { E } & 90 & 99 & 108 \\\text { C } & \text { End } & 85 & 100 & 115 \\\text { D } & \text { F } & 19 & 25 & 31 \\\text { E } & \text { End } & 91 & 100 & 115 \\\text { F } & \text { End } & 62 & 65 & 68\end{array}\end{array}$$ What is the estimated slack time for activity A?

A) 0 days
B) 20 days
C) 40 days
D) 60 days
E) 100 days