What is the description and code of the type of service that is performed the most often?
return services ;return how often #1 are performed ;return #1 where #2 is  the   most often ;return the   type of #3 ;return the   description of #4 ;return the   code of #4 ;return #5 ,  #6
['select', 'project', 'comparative', 'project', 'project', 'project', 'union']