What is the most elegant way to get a set of items by index from a collection?

Question

Given

IList indexes;
ICollection collection;

What is the most elegant way to extract all T in

Answer 1

    public static IEnumerable WhereIndexes(this IEnumerable collection, IEnumerable indexes)
    {
        IList l = new List(collection);
        foreach (var index in indexes)
        {
            yield return l[index]; 
        }
    }