Answer:
Cube.
Explanation:
We are asked to find the solid figure, which has congruent squares on all six sides.
We know that a solid, whose length, width, and height are equal in measure is known as cube.
Upon looking at our attached file, we can see that length, width, and height for the solid are equal to x units, which makes its each face a square.
We know that a cube is a three dimensional figure, which contains six equal squares of all six sides.
Therefore, cube has congruent squares on all six sides.