For a particular project, eight activities are to be carried out. Their relationships with other activities and expected durations are mentioned in the table below.
$\begin{array} {}\textbf{Activity} & \textbf{Predecessors} & \textbf{Duration (days)} \\ a & – & 3 \\ b & a & 4 \\ c & a & 5 \\ d & a & 4 \\ e & b & 2 \\ f & d & 9 \\ g & c,e & 6 \\ h & f,g & 2 \end{array}$
If the duration of the activity $f$ alone is changed from $9$ to $10$, then the
- critical path remains the same and the total duration to complete the project changed to $19$ days
- critical path and the total duration to complete the project remain the same
- critical path changes but the total duration to complete the project remain the same
- critical path changes but the total duration to complete the project changes to $17$ days