Hello Gamedev, I'm gonna start studying for the Oracle Certified Java Apprentice certification soon so I was taking a practice test to see what it was all about. Most of it was pretty straight forward and easy but there were a few questions that I just totally didn't get. I don't know if It's just not a high quality test, or, more likely, My self taught understanding of Java is a bit off in some ways. Here is one question that really confused me:

Q: Which of the following keywords is used to declare an instance variable?

A - abstract
B - Constant
C - Concrete
D - interface

I had no idea what the answer was so I guessed, I don't even remember what, but according to the test the answer was interface, which really confused me. I thought it was asking which Java keyword you use when your declaring an instance variable(I didn't know the declaration was what determined whether something was an instance variable or not at all, I thought it had to do with whether it belonged to an instance of a class).

can someone explain this to me? What do the mean 'using the interface keyword to declare an instance variable?'

And clearly something is wrong with my understanding of instance variables and maybe interfaces, based on the little paragraph above explaining my understanding of the topic can anyone correct me so I can comprehend the whole big picture a little better.

Thanks guys