parse portion of HTML - count of certain tag - C# RegEx code needed

This section of the HTML is of interest to me:

<select name="ctl00$ContentPlaceHolder1$dlStore" id="ctl00_ContentPlaceHolder1_dlStore" disabled="disabled" title="Store" style="text-align: left">
            <option value="NULL">Select Campus...</option>
            <option selected="selected" value="1">KSU ASHTABULA</option>
</select>

This will be surrounded by other HTML, but it is just this block of code that I want to extract and examine.

Within this block of code, above, I want to check for HOW MANY <option></option> pairings there are.  If there is only one I want to do one thing.  If there are more than one I want to do another thing.

So the logic would be:

(A) Isolate the portion of code above.  Perhaps use the existence of "dlStore" in the id to identifiy the <select></select> block
(B) in this block of code we isolate in (A), count how many times there is an <option></option> pairing.
(C) do something based on the count.


Please provide tested working C# source code if you can.

I am using C# in a windows app to do this....I will favor a working C# .NET response over something more generic.