To Fall Under
Intransitive verb and する verb
ぞくする
四年生の時は誰のグループに属していたの？
Whose group were you in when you were in grade four?
Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means belong so the verb vocab version is to belong to.
The reading is the one you learned with the kanji. This kanji is going to belong to you.