Answer
The next figure is the large square with a small square inside of it. It will have one small "leg" drawn in the center of the outline of the large square.
Work Step by Step
A group of large squares have a shape inside of them and a line (or lines) drawn on the outside of them. The lines on the outside are being referred to as "legs" in this explanation.
First, let's look at the shapes inside the large squares. They are: triangle, circle, square, triangle, circle, ...
By observing a pattern, the next shape should be a square. So, there will be the large outline of a square with a smaller square drawn inside of it.
Now, let's look at the "legs" on the outside of the drawing. There are either two legs at the corners of the outline or one leg at the center of the outline. The first has 2 legs, the second has 1 leg, the third has 2 legs, and so on...the pattern is 2, 1, 2, 1, 2,..., So, the next figure will have one leg.
Therefore, the next figure will have a small square drawn inside of the outline with a single leg in the center of the outline.
