c# - LINQ:子ノードが条件を満たすアイテム要素を選択する方法は?

Question

私のXMLは次のようになります。

 <order>
    <order_number>1N</order_number>
    <execution_data>
        <exe_date>11/01/2011</exe_date>
        <exe_name>Joe</exe_name>
    </execution_data>
    <execution_data>
        <exe_date>12/01/2011</exe_date>
        <exe_name>Mike</exe_name>
    </execution_data>
    <execution_data>
        <exe_date>8/01/2011</exe_date>
        <exe_name>Steve</exe_name>
    </execution_data>
</order>
<order>
    <order_number>2N</order_number>
    <execution_data>
        <exe_date>11/01/2011</exe_date>
        <exe_name>Rob</exe_name>
    </execution_data>
    <execution_data>
        <exe_date>12/01/2011</exe_date>
        <exe_name>Marko</exe_name>
    </execution_data>
    <execution_data>
        <exe_date>8/01/2011</exe_date>
        <exe_name>Sam</exe_name>
    </execution_data>
</order>
<order>
    <order_number>3N</order_number>
    <execution_data>
        <exe_date>11/01/2011</exe_date>
        <exe_name>Nick</exe_name>
    </execution_data>
    <execution_data>
        <exe_date>12/01/2011</exe_date>
        <exe_name>Ashley</exe_name>
    </execution_data>
    <execution_data>
        <exe_date>8/01/2011</exe_date>
        <exe_name>Marc</exe_name>
    </execution_data>
</order>


    public class ExecutionItem
    {
       public string Date {get;set;}
       public string Name {get;set;}
    }

    public class Response
    {
       public List<ExecutionItem> ExecutionItems{get;set;}
    }

order_number等しい注文を選択し、LINQ を使用してその注文から1Nすべてを取得する方法は?execution_data