Some of the words with "ọ" are pronounced with a diphthong resembling [aw], like học and đọc. You can check the pronounciations with the wiktionary (if you read IPA), for exemple https://en.wiktionary.org/wiki/h%E1%BB%8Dc that gives various exemples of pronounciation for this word. I don't know if it applies to other tones or what, though.
Seriously, we need native English speakers to check these answers. This solution sounds so bad. Any of the following would have sounded like fluent English but not this one. "Why are they publishing the book?... Why did they publish the book?... Why do they publish books?... Why are they going to publish the book?... Why are they going to publish the book?" But it's hard to learn when I don't really understand the intended meaning of this translation.
Well, except for "Why do they publish books?", all the translations you listed would be all legit, because Vietnamese has no grammatical tense, and all time references are done with adverbs and contexts, both of which are not present here.
For a language heavily dependent on context like Vietnamese, Duolingo, a translation-based platform, inherently does a really bad job. It is, as you can see, impossible to know the intended meaning. They could list all possible translations out, but that's certainly exhaustive and time-consuming (and data-consuming, too).