ummmm, i need help on a qesution can anyone help
An adverb clause, or a subordinate clause, is the one which cannot exist on its own, it has to be a part of the main clause, or else it sounds incomplete. The only such example here is B, because if you look at that clause on its own, it needs to be completed. A is just a weird construction meaning nothing. C is a fragment of a sentence. And D is an infinitive phrase.