is it possible to add rich content question?

You can use only limited TAGS like A, И, SPAN in question by default…

		'a'      => array( 'href'=>true, 'rel'=>true, 'name'=>true, 'target'=>true, ),
		'b'      => array(),
		'strong' => array(),
		'i'      => array(),
		'em'     => array(),
		'span'   => array( 'class'=>true ),
		'code'   => array(),
		'var'    => array(),
		'del'    => array( 'datetime'=>true, ),

Use filter

apply_filters('demadmin_sanitize_poll_data', $data, $original_data ); 

to change this…