Which VMU was activated on the 12 of September, VMU-3 or VMU-4?
return VMU ;return #1 that was  activated on the  12 of September ;return if #2 was  the  VMU-3 ;return if #2 was  the  VMU-4 ;return which is true of #3 ,  #4
['select', 'filter', 'boolean', 'boolean', 'comparison']