Which interface should you add the extension method to?

You are developing an ASP.NET Web page that will display the median value from a sequence of
integer values. You need to create an extension method to compute the median value. Which
interface should you add the extension method to?

A.
IComparer(Of T)

B.
IEnumerable(Of T)

C.
IEnumerator(Of T)

D.
IEqualityComparer(Of T)