Is it possible to filter specific select options?
I have a code :
<select id="adcategory" name="adcategory">
<option value="">Select</option>
<option value="25" class="dropdownparentcategory">Florida Atlantic University</option>
<option value="26">- Books </option>
<option value="27">- Electronics</option>
<option value="28">- For Rent</option>
<option value="17" class="dropdownparentcategory">Florida International University</option>
<option value="18">- Books</option>
<option value="19">- Electronics</option>
<option value="20">- For Rent</option>
<option value="1" class="dropdownparentcategory">Florida Tech</option>
<option value="2">- Books</option>
<option value="3">- Electronics</option>
<option value="7">- For Rent</option>
</select>
So if the variable for example $school = Florida Atlantic University than show only thoes options witch is till next school category ( .dropdownparentcategory ), so in this case they would be only :
<select id="adcategory" name="adcategory">
<option value="">Select</option>
<option value="26">- Books </option>
<option value="27">- Electronics</option>
<option value="28">- For Rent</option>
</select>
As you can see in this image :

Is it possible to create with jQuery?
This looks like potentially bad design. I would suggest moving to
<optgroup>[MDN] tags to group your drop down items:Then it’s trivially easy to select child elements;