Consider the following code fragment, which sets up the retrieval of an XML document named fish.xml and calls a function named showFish(): var xmlhttp = new XMLHttpRequest(); xmlhttp.open("GET", "fish.xml", true); xmlhttp.onreadystatechange = showFish(); xmlhttp.send(); Which line of code initializes the XMLHttpRequest object?

A.
xmlhttp.send();

B.
var xmlhttp = new XMLHttpRequest();

C.
xmlhttp.open("GET", "fish.xml", true);

D.
xmlhttp.onreadystatechange = showFish();