This is not possible with a standard dropdown, either a dropdown content control or a legacy dropdown field.
There is a workaround, which takes a bit of setup work but is then simple to use. It uses a "building block gallery content control", which works like a standard dropdown content control except that instead of text entries it displays all the building blocks from a specified gallery and category.
The setup involves creating three building blocks in a custom gallery, one for each color.
- If the form you're preparing isn't already saved as a template (*.dotx) instead of a document (*.docx) file, do that now.
- In an otherwise empty paragraph in the template or a document based on the template, turn on the display of nonprinting characters by clicking the ¶ button on the Home ribbon. Then press Ctrl+Shift+spacebar about 20 times to create a block of nonbreaking spaces.
- Select the block of spaces, but not the paragraph mark at the end of the line.
- Click the Shading button in the Paragraph group of the Home ribbon and select the red block in the Standard Colors section of the menu.
- With the block of spaces (now shaded red) still selected, press Alt+F3 to open the Create New Building Block dialog.
- Enter the name "Poor" for this red block, select the Custom 1 gallery (or any other numbered custom gallery), and create a category named "dropdown" (or any other name you like). Check that the Save In box shows the name of your form's template, not your Normal.dotm template.
- Click OK in each open dialog box.
- With the block of red spaces still selected, use the Shading button to change the color to orange. Press Alt+F3 again, enter the name "Acceptable", choose the same Custom gallery (the "dropdown" category should appear automatically, since it's the only one in that gallery), and click OK.
- Repeat the previous step, changing the shading to green and the name to "Exceptional". You're now done with creating building blocks. You can delete the block of spaces, which is no longer needed, and turn off nonprinting character display.
- In the body of the template, insert a building block gallery content control. While the control is selected, click the Properties button in the Controls group.
- In the Properties dialog, enter a title such as "Ratings". At the bottom of the dialog, set the Gallery dropdown to the name of the Custom gallery you used for the building blocks, and set the Category to "dropdown" or whatever you chose before. Click OK.
- Click the Design Mode button in the Controls group, and change the placeholder text of the content control to whatever you want it to say, such as "Choose a rating". Then click the Design Mode button again to turn it off.
- Copy the building block gallery content control and paste it into each place in the template where a rating is needed. Yes, you can paste it 50 times! You only have to do this once.
- Don't forget to save the template!
Each of the resulting controls can show the individual value for that rating: