I left off "the" which works sometimes but not others. It failed here. "cats drink water" "horses drink milk" works, but "boys eat apples" does not. Is it a human vs animal thing?
"I" is the plural of "il", "gli" the plural of "lo" (among other things); if you know how to differentiate between "il" and "lo" the rest should come natural.
this is not the only correct answer; "The children eat apples" must also be correct.
"I ragazzi mangiano mele." is "The boys eat apples." "I ragazzi mangiano le mele." is "The boys eat the apples."
The difference is the article "le" meaning "the".
So does Italian not require the use of articles all the time? Cause I've missed a few in the past for omitting them in situations (that I thought were) similar to this.
This is a complicated topic that isn't 100% clear when it comes to translation. The Italian language uses articles much more often than they are used in English. In fact in some scenarios, the English translation might not even make sense when translated directly using the articles.
The rule of thumb that I use is... Translate the sentence exactly how it is written from Italian to English. However when translating from English to Italian, always use the article "the". You will always be correct.
Italian to English: Translate verbatim
English to Italian: Translate using articles ("the")