Which Advisor has most of students? List advisor and the number of students.
return advisors ;return students  of  #1 ;return number of  #2 for each  #1 ;return #1 where #3 is  highest ;return students  of  #4 ;return number of  #5 ;return #4 ,  #6
['select', 'project', 'group', 'superlative', 'project', 'aggregate', 'union']