A form’s . . . . . . . . determines the border style of the form.

The correct answer is: A. FormBorderStyle Property

The FormBorderStyle property determines the border style of a form. It can be set to one of the following values:

• None – The form has no border.
• Fixed3D – The form has a three-dimensional border.
• Sizable – The form has a resizable border.
• FixedSingle – The form has a single-line border.
• FixedDialog – The form has a dialog box border.

The FormBorderStyle property is a property of the Form class. It is a member of the System.Windows.Forms namespace.

The FormBorderStyle property can be set at design time or runtime. To set the property at design time, use the Properties window. To set the property at runtime, use the SetStyle method.

The following code snippet shows how to set the FormBorderStyle property at design time:

Form myForm = new Form();
myForm.FormBorderStyle = FormBorderStyle.Fixed3D;

The following code snippet shows how to set the FormBorderStyle property at runtime:

Form myForm = new Form();
myForm.SetStyle(ControlStyles.Resize, true);
myForm.SetStyle(ControlStyles.Fixed3D, true);

The FormBorderStyle property is a read-write property.