"Lui mangia riso."
The slower sound clip sounds really weird. Almost like 'ariso'. Wasn't sure if it was supposed to be just riso or il riso.
I couldn't hear it either way, but on listening to the slower one I went with "il riso," and was marked wrong. It really sounded like "elriso."
Why not "Lui mangia il riso" since it seems that the article is mandatory in italian?
I agree with the previous comments regarding the clip sounding like 'il riso'
In this case, probably because it's referring to rice in general, not rice he's at this moment eating. I think (not sure) you could say "Lui mangia il riso", if it's the latter example, but at any rate, comparing rice and apples is not a very good comparison, since rice isn't quantifiable. Hope this helps.
How are we supposed to know what the context is? It seems it's a lucky guess as to whether to include the article or not, even more so with the questionalble speech synthesis.