Acceleration Problem: Need Help Solving!

[Workout]

Hello I have a link to the problem #2. The directions are shown by letter and I had to assign the letters to the pictures below. I am wrong.. can someone help me please?

http://i.imgur.com/lqEZFfl.jpg

 

[Basic_Physics]

1 and 2 is correct, but not 3,4 and 5.
Think of the sponge as a spring (backed by a solid material that does not move or give).