According to:
http://www.w3.org/TR/CSS21/selector.html#dynamic-pseudo-classes

Note that the A:hover must be placed after the A:link and A:visited rules, since otherwise the cascading rules will hide the 'color' property of the A:hover rule. Similarly, because A:active is placed after A:hover, the active color (lime) will apply when the user both activates and hovers over the A element.

Which I think results in the required order being:
link
visited
hover
active
However in the stylesheet.css the order is:

a:link {

   color: #006597;

   text-decoration: none;

}

a:active,

a:visited {

   color: #005784;

   text-decoration: none;

}

a:hover {

   color: #D46400;

   text-decoration: underline;

}