Activity $8$ is directly preceded by two activities$-$activity $7$ and activity $6.$ Activity $5$ has an expected time of five days and an estimated start $($ES$)$ time of day $6.$ Activity $6$ has an expected time of seven days and an ES time of day $7.$ Activity $8$ has an expected time of $10$ days. The EF for activity $8$ is$?$

$$ a$.$ Day $14$

b$.$ Day $26$

c$.$ Day $21$

d$.$ Day $24$

e$.$ Day $19$