"An apple and orange" should be correct as well, since there is no need to repeat the article.
For me as a German it is slightly confusing, that it is “appelsin” and not “eplesin”.
Obviously the word “appelsin” has the same heritage as in German meaning „apple from china“.
Because they have different genders. 'Eple' is neuter, thus takes 'et', whereas 'appelsin' is common and so takes 'en'.
When a boy orange loves a girl orange blah blah blah...hehe ok but I know what you mean. I was bored so I made up a sort of dumb joke
An unfortunate number of people here don't know the difference, so it's hard to be sure. :-(
I wrote "the apple and the orange" but it was wrong. Can you also put "the" or does it have to be "an"?