In what way does free float differ from total float ？（）
A．Free float is the amount of total float that does not affect the end date, whereas total float is the accumulated amount of free float.
B．There is no difference-the two terms are functionally equivalent.
C．Free float is the amount of time that a schedule activity can be delayed without delaying the early start of any immediately following schedule activities, whereas total float is concerned with delays that do not affect the project finish date.
D．An activity's free float is calculated by subtracting its total float from the critical path's total float.