It's difficult to tell, given the fuzziness and glare of that photo. But I've pulled up uncounted apple seedlings, and there's a lemon in the living room window, so I'll offer a guess:

Coleus: highly unlikely.
Apple: unlikely.
Lemon: probable.

Something else: possible.
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You might want to go to the Citrus forum to see what they say about whether lemons grow true from seed (apparently it depends on the variety, though it's more complicated than that), and how long you'll need to wait before they can flower and bear.

[Apples do not grow true from seed. You might get something good, or you might not.]

Yes, that blurry pic makes it very difficult, if not impossible to judge, but that said, a very easy tell for any citrus is that citrus leaves are very fragrant & perfume-y when crushed. You might try breaking off a bit & crushing it for a sniff test...

Definitely lemon!!

Apples will grow to have a reddish stem at first with rounder leaves. I know my response is 10 years late but I'm curious to find out what this little plant grew to be!

Id say apple. My lemon tree sprouts have very smooth leaves. My apple sprouts are more jagged. And, yes, you absolutely can grow apple trees from seeds, it's just a little more difficult, as they generally need a cold front to germinate. I just had about 4 of 6 sprout. Had to put the seeds in fridge for a few days.

" yes, you can grow apple trees from seeds"

But since they are all hybrids it is hardly worth the effort as what you get will not be the same as the seed parent and often inedible or not worth the time it takes to get to fruiting maturity.

Can make for an entertaining experiment, tho!