Call A Function From An <option> Element

I'm trying to call a function depending on which <option> is selected from <select> dropDownList. Here's what i've tried:

function emailPrefs() {
If (document.frmAmandaPrefs.ddlFormat.selectedIndex == 3); {
hideLayer('emailPrefHolder');
} Else If (document.frmAmandaPrefs.ddlFormat.selectedIndex == 2); {
showLayer('emailPrefHolder');
} Else If (document.frmAmandaPrefs.ddlFormat.selectedIndex == 1); {
showLayer('emailPrefHolder');
}}

And my select looks like this:

<SELECT class="formtext" id="ddlFormat" name="ddlFormat" runat="server" onchange="emailPrefs()">
<OPTION value="2">HTML</OPTION>
<OPTION value="1">TEXT</OPTION>
<OPTION value="3">RSS</OPTION>
</SELECT>

Any ideas?