There are 3 type of patterns which are being followed for fig.(1) to fig.(2), fig.(2) to fig.(3) and fig.(3) to fig.(4) respectively. And then these 3 patterns are getting followed for the rest of the figures.

The change in a particular design is occurring at the right most position and middle position alternatively irrespective of the pattern.

Pattern 1: Right-most design will come at the left most position and other letters will shift one position in the right direction. After shifting right-most design will get changed.

Pattern 2: Designs at the extreme positions will exchange their position and designs at the 2nd last extreme positions will exchange their position. Middle position letter will get changed.

Pattern 3: First two letter will exchange their position and the right-most letter will come at the middle position and remaining shift their position in the right direction. Now this time, right-most design will get changed.

Above mentioned 3 pattern will be followed alternatively for further figures and hence, accordingly answer will be D