Answer: (A) 1 Foot
Explanation:
Travel per second = Distance/Time
So Look at the highest part of the graph. It says 6 Feet travelled after 6 seconds.
Thus 6 Feet / 6 Seconds = 1 Foot per second
This can be confirmed by the fact that 2 feet is travelled in 2 seconds, and 4 feet is travelled in 4 seconds, based on the graph.
Hope this helps!