Given： 3.public class MyTagHandler extends TagSupport { 4.public int doStartTag（） { 5.// insert code here 6.// return an int 7.} 8.// more code here ... 18.} There is a single attribute foo in the session scope. Which three code fragments，inserted independently atline 5，return the value of the attribute？（）

A. Object o = pageContext.getAttribute（"foo"）；
B. Object o = pageContext.findAttribute（"foo"）；
C. Object o = pageContext.getAttribute（"foo"，PageContext.SESSION_SCOPE）；
D. HttpSession s = pageContext.getSession（）；Object o = s.getAttribute（"foo"）；