Changing an argument to a var and vice-versa

Hello,

I am using Instantiate (object, position, rotation);

I have 3 objects defined in a public class like this:

 public class Objects
 {
    public GameObjects Name1, Name2, Name3;
 }
 private Objects objects;
 

I am using this to define their name in another var.

 private string var;
 var = "Name" + Random.Range(1, 4);

Then I am using this var to access the name of the object in the Object public class like this:

 Instantiate (object.var, position, rotation);

And I an getting an error. I am very new to the Unity, C# and programming in general and I have been doing the tutorials for a week, then I stumbled upon this idea to increase the number of diferente enemies, but I don't know how to aply this or if it is even applicable.

What I think is happening is that the Instantiate sees var as a string variable and isn't able to relate it with anything inside the Object class. What I don't know is how I can make he relate to it.

Thanks in advance.