You use the . . . . . . . . tool to add a checkbox to a form.

The correct answer is D. Checkbox.

A checkbox is a type of input control that allows users to select one or more options from a list. It is represented by a small box that can be checked or unchecked. When a checkbox is checked, it indicates that the user has selected the option. When a checkbox is unchecked, it indicates that the user has not selected the option.

Checkboxes are often used in forms to allow users to select multiple options. For example, a form might ask users to select their favorite colors. In this case, the form might have a checkbox for each color, and users could check the boxes for the colors that they like.

Checkboxes can also be used to allow users to select a single option from a list. For example, a form might ask users to select their gender. In this case, the form might have a checkbox for each gender, and users could check only one box.

To add a checkbox to a form, you can use the Checkbox tool in the Form Editor. The Checkbox tool is located in the Controls group on the Insert tab.

To use the Checkbox tool, follow these steps:

1. In the Form Editor, click on the Insert tab.
2. In the Controls group, click on the Checkbox tool.
3. Click on the form where you want to add the checkbox.
4. A checkbox will be added to the form.
5. To edit the checkbox, click on it.
6. In the Properties window, you can change the text that appears next to the checkbox, the value of the checkbox, and other properties.

Here is a brief explanation of each option in the question:

• A button is a type of input control that allows users to perform an action. For example, a button might be used to submit a form or to open a new window.
• A radio button is a type of input control that allows users to select one option from a list. Radio buttons are often used in forms to allow users to select a single option from a list.
• An option is a value that can be selected by a user in a form. Options are often used in forms to allow users to select a single value from a list.
• A checkbox is a type of input control that allows users to select one or more options from a list. Checkbox are often used in forms to allow users to select multiple options.