Elegant way to combine multiple collections of elements?

Question

Say I have an arbitrary number of collections, each containing objects of the same type (for example, List foo and List bar).

Answer 1

The only way I see is to use Concat()

 var foo = new List { 1, 2, 3 };
 var bar = new List { 4, 5, 6 };
 var tor = new List { 7, 8, 9 };

 var result = foo.Concat(bar).Concat(tor);

But you should decide what is better:

var result = Combine(foo, bar, tor);

or

var result = foo.Concat(bar).Concat(tor);

One point why Concat() will be a better choice is that it will be more obvious for another developer. More readable and simple.