Which of the following describes the reason for using this attribute?

You work as a developer at ABC.com. The ABC.com network consists of a single domain named
ABC.com. You make use of CSS3 and HTML5 for development purposes.
You are in the process of creating a client web form for ABC.com. The form contains an HTML
with the necessary validation. The validation includes the required attribute.
Which of the following describes the reason for using this attribute?

A.
It marks an element that can’t be submitted without a value.

B.
It sets or retrieves a comma-separated list of content types.

C.
It retrieves a collection of all a objects that have a name and/or id property.

D.
It sets or retrieves whether the option in the list box is the default item.

Explanation: