Tom is making changes to his company’s Web site. Because he likes the way the markup is styled, he copies the following into another section of the page:
<div id=”subsection”> This section is under construction</div>
Why does the home page not validate properly?

A.
Element attributes must be declared in the style sheet.

B.
The <div> tag was not closed properly.

C.
A <div> tag can be used only once in each document’s markup.

D.
An ID attribute can be applied to only one element in a document.