Which answer figure will complete the pattern in the question figure?

In the top two boxes of the question figure, a slant line is connecting one corner to the other one. Similar logic will be applied in the bottom two boxes. So as per the logic, the required slant line is not available in option (c) and (d). Hence these options can be eliminated.

The relation between the rectangles of the top two boxes is that they are diagonal to each other. Similar logic will be applied in the bottom two boxes. It will eliminate the option (a). Now option (b) is remaining which will be the correct answer.