Several months late, but better that than never.

Honest question, how can you tell an orange slice from a lemon slice in a greyscale image when there's no whole orange/lemon nearby to serve as implication? I tagged the former because that's the first thing that came to my mind, but I'm not sure.

In this case, lemon slice is a safe bet, since it's the fruit most frequently used to garnish drinks.

Overall size is also a good indicator, since you don't find orange slices as tiny as that.