link中如何实现随机n选1？

link中如何实现随机n选1？

var query = lists[0].Select(x => new int[] { x });
for (int i= 1; i < lists.Count; i++)
{
query = lists.SelectMany(x => query.Select(y => y.Concat(new int[] { x })))
}
怎么修改？

最后加上query = query.Select(x => x.OrderBy(_ => Guid.NewGuid()));