In my view, there are no sentences which are true.
My sentence is "Which is your favourite fruit, apples or an oranges?" or "Which is your favourite fruit, an apple or an orange?"
I'm not sure about that. But I infered those senteces from following theories :
We can use a/an in a noun phrase to classify something. We were asking about "a kind of fruit", So maybe we could convert to "your favourite fruit" .
We can use a/an in a generalization. We can also use a plural or uncountable noun on its own in the same significance.
So I can use "an apple" or "apples". The only difference between them is an apple means 'any apple' or 'a typical apple' and apples means 'all apples.
Sorry, all of them are inference, I'm not sure absolutely.
Student or Learner