Correct Option: A

<isindex> is an obsolete HTML element. It puts a text field in a page for querying the document. <keygen> element exists to facilitate generation of key material and submission of public key as part of HTML form. It is designed to use with web-based certificate management systems. It includes all the global attributes like autofocus, challenge etc. The rendering of text between start tag and end tag is done by <listing> element. A scrolling text can be displayed by <marquee> element.