Overview
Single select fields allow users to select one entry from a list of pre-set choices, instead of typing one. Zoho Creator supports the following types of single-select fields:
- Drop-down: A drop-down list provides the user with many choices in a limited space. It allows the user to choose one (and only one) option from the list of choices. A drop-down list takes two or more clicks (to open the list, scroll, and select) to make a selection. The user makes a selection by clicking in the list. Once an item is clicked, it becomes highlighted indicating that it is the current choice.
- Radio button: Radio-buttons also allow the user to choose only one option from a list of choices displayed. They are easier to read and require fewer interactions/clicks to use. Sure, they take up more space, but in Forms where maximizing space is not an issue, but visibility of available options is, then radio buttons would be a better UI choice. The radio buttons can also be arranged in one, two or three columnar layouts.
Screen-shot of a sample form with radio-button and drop-down list choices

Also refer the topic, conditional drop-downs to populate list values dynamically
Configuring a drop-down field type
- Drag-n-drop the Dropdown field type to the editor area.
- The Adding 'Dropdown' screen is displayed as shown below.
- In the Label Name textbox, enter the Field Label name that will be displayed in the form.
- In the Enter Choices textarea, enter the choices to be listed for this field, one per line.
- Click on Options and select the field configurations. If the want the drop-down choices to be displayed in alphabetical order, select the checkbox "Show choices in alphabetical order". Refer the link Field Configurations to learn more about each configuration.

- Click Done to add the field with the specified configurations.
- To edit the field configurations or to delete the field or to add field action scripts, move mouse over the field and click on the Edit this field option, as shown below.

- When you Access the application, the drop-down field will be displayed in your form with the specified choices. Users can open the list and make the required selection.
Configuring a Radio button field type:
- Drag-n-drop the Radio field type to the editor area.
- The Adding 'Radio' screen is displayed as shown below.
- In the Label Nametextbox, enter the Field Label name that will be displayed in the form.
- In the Enter Choices textarea, enter the choices to be listed for this field, one per line.
- Click on Optionsand select the field configurations.
- By default the radio buttons will be arranged as one columnar layouts. To arrange them in two or three columns, select the required option from the "Field Layout" list box.
- If you want the drop-down choices to be displayed in alphabetical order, select the checkbox "Show choices in alphabetical order". Refer the link Field Configurations to learn more about each configuration.

- Click Done to add the field with the specified configurations.
- To edit the field configurations or to delete the field or to add field action scripts, move mouse over the field and click on the Edit this field option, as shown below.

- When you Access the application, the radio button field will be displayed in your form with the specified choices. Users can make the required selection.