Choose one favourite within a group with 一番
You can already choose between two options. Now say 一年でいつが一番好きですか and answer 秋が一番好きです. First point to 一年で as the group within which you choose.
1. で marks the group here
In group + で, で means ‘within’ or ‘among all members of that group’. スポーツで establishes ‘within the category of sports’, and 一年で means ‘within one year’. This is a new function of で in the course sequence.
This で is not the location marker that lesson 32 will use for the place of an action. スポーツで is not a place where someone performs an action; it only limits the choice category. Therefore, do not treat location で as a required rule in this lesson.
スポーツで何が一番好きですか。
一年でいつが一番好きですか。
2. 一番 comes before the quality
一番 means ‘the most’ or ‘the best’ within the named group. Put it directly before the quality or preference: 一番好き, 一番きれい, 一番高い. The final word determines what the highest rank concerns.
In the answer, the selected option comes before が: 秋が一番好きです. が marks which item is the top choice. The group need not be repeated when the question has already made it clear.
秋が一番好きです。
ホイアンが一番きれいです。
3. Choose 何, どこ, or いつ
Use 何 for a thing or type: スポーツで何が一番好きですか. Use どこ for a place: ベトナムの町でどこが一番きれいですか. Use いつ for a time or period: 一年でいつが一番好きですか.
The question word comes before が and asks which member of the group has the highest rank. 何が asks ‘what’, どこが ‘which place’, and いつが ‘which time’. Answer with the same type of information: a sport, a place, or a season/time.
4. Two options or a whole group
Lesson 24 compares two named options with どちら and answers with のほうが or どちらも. Lesson 25 chooses one highest-ranking item within a larger group: group で + question word が一番. Therefore, do not list every sport separately when スポーツで already establishes the category.
Compare 秋のほうが好きです with 秋が一番好きです. The first chooses autumn over one other named option; the second makes autumn the favourite within the known group. 一番 therefore needs a clear group, either in the sentence or in the conversational context.
春と秋とどちらが好きですか。
一年でいつが一番好きですか。
5. Track the category and answer type
Read the existing story about a favourite time of year and favourite sport. First identify the category with で, then the question word, and finally the selected option in the answer. The story also briefly reviews the two-choice form from lesson 24.
Then return and make a new question with one of the three question words taught. The final check explicitly supplies the category and answer type; you do not need to add a reason or a new grammatical connection.