var tabs = new Array("C1","C2","C3" ,"C4" ,"C5");

  function displayTab(tabName) {
    for ( i = 0; i < tabs.length; i++ ) {
      var tab = document.getElementById(tabs[i]);
      if ( tabName == tabs[i] ) {
        tab.style.display = 'inline';
      } else {
        tab.style.display = 'none';
      }
    }
  }