PageBlockSectionのselectOptionの配置
また。だから、これを取る:<apex:pageBlockSection id= clientsList title= Clients List rendered= {!searchCriteria.Search_Type__c ='Clients List'} columns= 1 >
<apex:pageblocksectionitem>
<apex:selectList value= {!selectedUser} size = 1 multiselect= false >
...
visualforce selectlist selectoption