For some reason, I could not do the Homework 5.4.  This is what I have:

Section II.

Consider two lists in HTML as follows:

<ul id="list_a">
    <li id="item_1">Item 1</li>
    <li id="item_2">Item 2</li>
</ul>

<ul id="list_b">
    <li id="item_3">Item 3</li>
    <li id="item_4">Item 4</li>
</ul>

It's fixed. Please try again and see if you can do the assignment.