HTML5中doctype标签的正确定义是（ ）
A.<!DOCTYPE html PUBLIC "-//W3C//DTD// XHTML 1.0 Transitional//EN" "http://w3.org/TR/xhtml1-transitional.dtd"> B.<!DOCTYPE html PUBLIC "-//W3C//DTD// XHTML 1.0 Transitional//EN" "http://w3.org/TR/xhtml4/loose.dtd"> C.<!doctype html5> D.<!doctype html>正确答案D
