Five jobs are ready for processing at time zero through a workstation. The details of the processing time and the due date of completion is provided in the following table.

Job

Processing Time $($days$)$

Due Date

$1$

$8$

$12$

$2$

$4$

$9$

$3$

$3$

$6$

$4$

$7$

$7$

$5$

$5$

$20$

Using the shortest processing time $($SPT$)$ rule, it can be concluded that the average flow time for these five jobs is $\_\_\_\_\_.$

a$.$ more than $8$ but less than or equal to $10$ days.

b$.$ more than $10$ but less than or equal to $12$ days.

c$.$ more than $12$ but less than or equal to $14$ days.

d$.$ more than $14$ but less than or equal to $16$ days.