To create the field, follow these steps:
1. In the navigation pane, click on Settings.
2. In the Customization group, click on Customizations and then click on Customize the System to open the default solution.
3. Expand the Entities component and then expand the appropriate entity.
4. Click on the Fields section and then click on New.
5. In the new Field form:
a. Provide a display name in the Display Name field.
b. Specify the Type as Option Set.
c. Next to Use Existing Option Set, click on New.
d. In the New Global Option Set pop-up window, provide a display name.
e. In the Options section, click on the Add icon (a green plus sign) to add a new option and provide a label for the option in the Lable field.
f. Continue to add options to meet your requirements.
g. Once you have finished with adding the options, click on Save and Close to close the New Global Option Set pop-up window.
6. Click on Save and Close.