Answer:
The answer is : 6 by 6 square and 2 by 2 square.
Step-by-step explanation:
The given figure of 3 by 3 boxes is similar to 2 by 2 boxes square and 6 by 6 square boxes.
These are cubes as these figures have same number of cubes at each side like 3 or 6.
The other two figures are 3 by 4 or 4 by 3, so they are not like 3 by 3.
So, the answer is : 6 by 6 square and 2 by 2 square.