Answer
See the detailed answer below.
Work Step by Step
Looking at the sky through section (1), we will see blue everywhere since all other colors will be absorbed by the blue sheet.
Looking at the sky through section (3), we will see red everywhere since all other colors will be absorbed by the red sheet.
Looking at the sky through section (2), we will not be able to see clearly. So it will be black since all colors will be absorbed by the red sheet except the red light will penetrate to the blue sheet which will absorb it as well. So no light color reaches your eye.
