jQuery $.parseXML calling XML invalid but it passes XML validators

I am trying to load an xml file using jQuery. The file is reported as valid when tested using validator websites. However, when I try to $.parseXML on the file, I get the following error:

Uncaught Error: Invalid XML: questions.xml

Here is the code I'm using:

var xml = $.parseXML('questions.xml');

And here is the XML in questions.xml:

<?xml version="1.0" encoding="UTF-8"?>
    <questionnaire defaultLanguage="english" xmlns="http://localhost/questionnaire" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://localhost/questionnaire
                        questions.xsd">
        <question id="index" type="other">
            <content>
                <default>Hi</default>
                <language type="spanish">Hello</language>
                <language type="russian">Hi</language>
            </content>
        </question>
        <question id="c01-q01" qId="Q0301" type="compliance">
            <content>
                <default>Hi</default>
                <language type="spanish">Hello</language>
                <language type="russian">Again</language>
            </content>
            <answer id="1" color="green">
                <default>Yes</default>
                <language type="spanish">sí</language>
                <language type="russian">Да</language>
            </answer>
            <answer id="2" color="red">
                <default>No</default>
                <language type="spanish">no</language>
                <language type="russian">Нет</language>
            </answer>
        </question>
        <question id="c01-q02" qId="Q0302" type="compliance">
            <content>
                <default>Hiyo</default>
                <language type="spanish">What?</language>
                <language type="russian">Yolo</language>
            </content>
            <answer id="1" color="red">
                <default>Please</default>
                <language type="spanish">Fix</language>
                <language type="russian">Me</language>
            </answer>
            <answer id="2" color="red">
                <default>I'm</default>
                <language type="spanish">Scared</language>
                <language type="russian">Of</language>
            </answer>
            <answer id="3" color="yellow">
                <default>Dark</default>
                <language type="spanish">Yolo</language>
                <language type="russian">Mole</language>
            </answer>
            <answer id="4" color="yellow">
                <default>Is</default>
                <language type="spanish">Helping</language>
                <language type="russian">Organization</language>
            </answer>
        </question>
    </questionnaire>