Translation:Which do you like better, pork or beef?
I might be totally wrong, but as far as I know, there is no comparative form in several Asian languages. So in order to say "A is bigger than B", you would say something like "Compared to B, A is big".
Or, in this case, "When it comes to A and B, which one do you like?" = "Which one do you prefer / like better, A or B?".
"Which is better" is basically implied in Japanese, either through the direct translations "which is good" (どちらがいいですか), or the comparative より form as a statement (ふたにくよりぎゅうにくのほうが好きです= I like beef more than pork, and the literal translation would be "I like beef compared to pork."
When it comes to these "X と X, どちらが好きですか" sentences, Duo is both incredibly picky and inconsistent with the answers they'll accept. The "accepted" structure for this sentence actually gets marked wrong for similar sentences later on, and vice versa. And after seeing people "report" on these issues from over six months ago, but seeing almost no changes since then, I'm starting to doubt whether reporting makes a difference.
Duolingo is just a computer and can only recognise whether or not a submitted translation matches one of the accepted translations, not whether or not it matches one of these translations with the options reversed.
Considering all the possible translations for this sentence, I think it's unreasonable to expect them all to have variations that switch the two options around from how they are in the Japanese sentence, especially since the "beef or pork" isn't any more inherently grammatical in English than the order in the Japanese sentence.
This Japanese sentence should have "方が/houga" to suggest this is a comparative question at all. I'm a native Japanese and translated the sentence as : Pork and beef, which one do you like? and DL didn't accept it.