Enthuware

I'm not sure I agree with the 1st answer, "low coupling", which I assumed to be the same as "loose coupling".

"Using a reference variable of an interface type" to me is very tightly coupled.

Let me know if there is something I am missing.

You did not quote the complete option. It says, "Using a reference variable of an interface type instead of the class implementing that interface."

Using an interface is indeed low coupling as compared to using the class.

HTH,
Paul.