Once the Total Cost at Either the High or Low

Once the total cost at either the high or low level of activity has been found, fixed cost can be found by

A) subtracting the variable cost per unit of activity from the total cost.
B) subtracting the total variable cost from the total cost.
C) adding the change in cost from the low to the high level of activity.
D) multiplying the variable cost per unit of activity times the low level of activity.
E) none of the above.