To solve this problem, we need to identify the pattern in the series of figures and find the figure that logically follows the sequence.

Let's analyze the given problem figures one by one:

1. 

   The first figure is a simple triangle.

2. The second figure is a triangle containing a smaller square.

3. The third figure is a standalone square.

4. The fourth figure is a pentagon containing a smaller pentagon.

5. The fifth figure is a simple pentagon.

Now, let's identify the pattern:

• The sequence starts with a simple shape (triangle, square, pentagon).
• This is followed by the same shape containing a smaller shape inside it.
• The sequence of shapes seems to be moving from triangle to square to pentagon.
• Finally, the last figure completes with just the simple shape without any smaller shapes inside.

To complete the series, the next figure should logically be a standalone square, given the pattern of alternating between shapes with and without smaller shapes inside them.

Given the options, the correct answer is:

This option matches the logical continuation of the sequence.