The return type of the members on an Interface Implementation must match exactly the interface definition?

Question

According to CSharp Language Specification.

An interface defines a contract that can be implemented by classes and structs. An interface does not p

Answer 1

You can do something like this:

 interface ITest
{
    IEnumerable Integers { get; set; }
}

class Test : ITest
{
    public IEnumerable Integers { get; set; }

    public Test()
    {
        Integers = new List();
    }
}