For an activity in a CPM analysis, the Early Finish time is $8$ and the Late Finish time is $10.$ Which of the following statements is true?

Question $9$ options:

a$)$

The slack for this activity is $2.$

b$)$

The duration of this activity is $2.$

c$)$

The late finish time is $12.$

d$)$

The activity is on the critical path