Answer:
a. Free float
Step-by-step explanation:
Free float is defined as activities that are not on the critical path of project completion. There is usually a difference between their early start date and late start date.
These activities can be delayed without impacting on the project finish date.
Float is also called slack, and involves 3 tyoes: total float (difference between finsihing date of the last item on critical path and project closing date), negative float (when the expected end date of last activity is after the project closing date), and free float.