(this may seem to be a simple question for native speakers as I think they don't even think about it, but it's not so clear for me)
In formal language, should it be written with or without "the" in the following cases?:
1) "(The) question 1 was asked in order to identify..."
2) "Answers to (the) question 1 were..."
3) In the label below the figure: "(The) question 1"
When cardinal numbers follow nouns as in your example, it is not necessary to use the definite article the before the noun as Question 1 itself is unique and you don't need to specify it further. There is only one Question 1 in your test.
The same rule applies when you indicate a hotel room number. You don't say "the room number 505, you just say "room number 505" as there is only one room that has this number in the hotel.
Question 1 in these contexts is effectively a "proper noun" (it identifies one specific thing).
For the same reason why we don't refer to the1 OP as the Riko, we don't use a definite article when referencing Question 1.
1 Note that OP normally stands for Original Poster (the person who originally posted the question). Sometimes it's Original Post (the question itself), but I don't usually use it in that sense myself.
In this particular context, it's a matter of intended nuance whether to include the before OP. It depends on whether the writer is thinking "locally". Within the context of a single question, OP identifies a single individual (so in this case, OP corresponds to the one-and-only Riko, and doesn't require an article).
But if the writer is thinking in broader terms (where OP more "generically" references anyone who posts a question), the definite article is required, as he's talking about a specific OP (this one, Riko).
