Explanation:
it decreases the fastest, where it drops the most feet in the same period of time.
the dots are made in 2 seconds intervals.
between the seconds 6 and 8 the ball drops from 65 ft to 25 ft (a drop of 65 - 25 = 40 ft).
bergen the seconds 8 and 10 the ball drops from 25 ft to 5 ft (a drop of 25 - 5 = 20 ft).
and then between the seconds 10 and 12 the ball drops from 5 ft to 0 ft (a drop of 5 ft).
so, A is the right answer. with 40 ft in 2 seconds the ball is dropping the most (= the fastest) between the seconds 6 and 8. which means the slope is negatively the steepest there = the height is decreasing the fastest.