The main Property of radio button box is . . . . . . . .

The correct answer is: A. check

A radio button is a type of input control that allows users to select one option from a set of mutually exclusive options. The main property of a radio button is that it can only be in one of two states: checked or unchecked. When a radio button is checked, it is selected and the other radio buttons in the group are unchecked.

The other options are incorrect because:

• B. value is the value that is associated with the radio button. It is used to identify the selected option when the form is submitted.
• C. stretch is not a property of a radio button.
• D. load picture is not a property of a radio button.