C# - IEnumerable to delimited string

var delimitedString = selectedValues.Aggregate((x,y) => x + ", " + y);

return list.Aggregate( new StringBuilder(),
                               ( sb, s ) =>
                               ( sb.Length == 0 ? sb : sb.Append( ',' ) ).Append( s ) );

string.Join(", ", string[] enumerable)

var delimitedString = string.Join(",", checkboxList.Items.Where(i => i.Selected).Select(i => i.Value).ToArray());

items.Aggregate((accum, elem) => accum + ", " + elem);

StringBuilder sb = new StringBuilder();
    foreach(ListViewItem item in checkboxList.SelectedItems) {
        if(sb.Length > 0) sb.Append(',');
        sb.Append(item.Text);
    }
    string s = sb.ToString();

string[] toDelimit = CallSomeFunction();
return toDelimit.Aggregate((x, y) => x + "," + y);