The first figure has X sides. The second figure has X-1 sides. The third figure is the same but is rotated 90 degrees anticlockwise. The last row of figures is irrelevant when solving the question.
Let’s look at the first row:
The first figure has 4 sides, the second figure has 3 sides, the third figure has 3 sides and has been rotated 90 degrees anticlockwise.
Let’s look at the last row:
We are missing the first figure, the second figure has 7 sides, the third figure has 7 sides and has been rotated 90 degrees anticlockwise.
So, the missing figure has 8 sides, the only figure that has 8 sides is the star.

This question is a non-verbal aptitude question. Try a free Non-verbal Aptitude Test at Aptitude-test.com.