Why on earth is the correct answer L'homme mange la viande, instead of l'homme mange de la viande
Why not: "L'homme mange du viande" ?
Because it's not "The man is eating some meat", yes it's grammatically correct and you can use it, but this sentence says "the" and not "some", and du means "some".
This "de la viande" "la viande" is really confusing =~. But Ok. I'll get over it.