Which three EL expressions, inserted at line 15, are valid and evaluate to "3"?

Given:
11. <%
12. request.setAttribute(“vals”, new String[]{“1″,”2″,”3″,”4”});
13. request.setAttribute(“index”, “2”);
14. %>
15. <%– insert code here –%>
Which three EL expressions, inserted at line 15, are valid and evaluate to “3”? (Choose three.)

A.
${vals.2}

B.
${vals[“2”]}

C.
${vals.index}

D.
${vals[index]}

E.
${vals}[index]

F.
${vals.(vals.index)}

G.
${vals[vals[index-1]]}

Explanation: