Here's a simple way to make multiple select fields dependent on one another. When a value is selected in one it is disabled in the others and cannot be selected.

dependent_selected.coffee

$.fn.dependentSelect = ->
  $(@).addClass('dependent')
  
  @each ->
    $(@).data('pre', $(@).val())
    
    @disableOthers = ->
      $('select.dependent')
        .not($(@))
        .find("option[value=#{$(@).val()}]")
        .prop('disabled', true)
        
    @disableOthers()
  
    $(@).on 'change', (e) => 
      $target = $(e.currentTarget)
      prev    = $target.data('pre')
      
      $("select.dependent option[value=#{prev}]")
        .prop('disabled', false)
      
      @disableOthers()
    
      $target.data('pre', $target.val())

Try it out on this here