To answer this question, you need to understand how comments are inserted into an XML document. Let's go through each option to understand why it is correct or incorrect:
Option A) - This option is correct because it uses the correct syntax to insert comments into an XML document. In XML, comments are enclosed within `` tags.
Option B) This is a comment - This option is incorrect because it does not use the correct syntax for comments in XML. XML comments should be enclosed within tags, not tags.
Option C) -This is a comment-> - This option is incorrect because it does not use the correct syntax for comments in XML. XML comments should be enclosed within tags, not and -> tags.
Option D) All of the above. - This option is incorrect because options B and C do not use the correct syntax for comments in XML.
The correct answer is A) . This option is correct because it uses the correct syntax to insert comments into an XML document.