$8-$ Consider the following project:

The expected duration and variance for activity $D$ are:

a$)8$ and $1\mathrm{.}33$ weeks

b$)8$ and $1\mathrm{.}78$ weeks

c$)10$ and $1\mathrm{.}33$ weeks

d$)10$ and $1\mathrm{.}78$ weeks

e$)$ None of the above