Which code segment should you use?

A Web page includes the HTML shown in the following code segment.

You need to write a JavaScript function that will dynamically format in boldface all of the hyperlinks in the ref span. Which code segment should you use?
A. $("#ref").filter("a[href]").bold();
B. $("ref").filter("a").css("bold");
C. $("a").css({fontWeight:"bold"});
D. $("#ref a[href]").css({fontWeight:"bold"});