// This function should return an array of the value properties of all the selected options
function getSelectedValues() {
         // Initialize an empty array to store the values
	 var selectedValues = []
         // grab all the selected option elements and store them in a variable
	    , $selected = $('.question').children('option:selected');

	 $selected.each(function(){
              // this = the selected element. this.value = the value property
              // the push method adds its argument to the end of an array
	      selectedValues.push(this.value);
	 });

         // Send the results out into the ether
	 return selectedValues;	 
}
 
// This grabs all the disabled options and changes their disabled property to the empty string   
function clearDisabled() {
    $('.question').children(':disabled').attr('disabled', '');
}

// This function disables all the options that are in the array it gets passed    
function disableSelected(selectedValues) {
         // This probably wasn't necessary, but it's good practice to build things like this into your code in case you reuse it in ways you didn't expect. You could add a different default value
	 sv = selectedValues || [];
      
         // For each value in the array, we get all the options whose value is the same as that value, but filter out the one that is actually selected
         // Then we change those elements to disabled
	 for (var i=0;i<sv.length;i++) {
	 $('.question').children('option[value=' + sv[i] + ']').not(':selected').attr('disabled', 'disabled');
	 }
}
    
$(document).ready(function(){
	 // OK, the DOM is ready to manipulate, so let's call all those functions we just assigned:
         // When any of the selects change, do some stuff:	
	 $('.question').change(function(){
                 // First find all the values that have been selected, and store them as an array
		 selectedValues = getSelectedValues();
                 // Then make all the options enabled
		 clearDisabled();
                 // Then pass the selected values we got earlier to the function that disables those values everywhere they are not selected
		 disableSelected(selectedValues);	    
	 });	
			
});