Limit what Type’s can be passed to method through interface

How to pass a type into a method that inherits a specific interface.

Example

I have an interface

public interface iBase
{
    void DoWork(object t);

}

I have a class that inherits the interface

public class WorkerClass : iBase
{
    public void DoWork(object t)
    {

    }
}

The following code uses the 2 classes above

class Program
{
    static void Main(string[] args)
    {
        Start(typeof(WorkerClass));
    }

    public static void Start(Type type)
    {
        iBase workerClass = (iBase)Activator.CreateInstance(type);

        workerClass.DoWork("tst");
    }
}

The above code works, but I want to make it so the Start's input parameter (Type type) only accepts type’s that are inherited from iBase. At present "type" will accept any type which is not what I want.