A

To determine which glass allows the word 'excellent' to be visible, we need to consider the colors used.
1. The word 'excellent' is written in red pencil.
2. The red glass will filter out the red color, meaning it is difficult to see the word 'excellent' through it because red light is absorbed by the red glass.
3. Conversely, the green glass will allow other colors to pass through but will not block the red pencil's color.
4. Therefore, the word 'excellent' can be seen through the green glass because it does not interfere with the red color.

Hence, the correct answer is the green glass.