How you going?

"Hey !
How u guys going? "
Its how Australians greet you whenever you come into shops.
First few days here, I was quite stupefied. What the? How am I going?

Should the answers be:
A. Got here by car
B. Not going anywhere
C. Can u please repeat the question, I didnt get you.
D. Hi ...?

So for quite sometime, my answer was D.
Further observations for the past months found that the correct way was something like either : "I'm good, How you going." OR "Not too bad myself, How you going. "
Oh well. There should be a handbook somewhere.

Anyway. Why am i talking about this.
Just to update that..I sat my IELTS exam last Saturday!! Wehoooo.
I promised myself I wouldn't freak out but I did.