Which of the following is valid consideration?Try to state t

Consideration is the concept of legal value in connection with contracts。It is anything of value promised to another when making a contract。It can take the form of money,physical objects,services,promised actions,abstinence from a future action,and much more。Under the notion of "pre-existing duties," if either the promisor or the promisee already had a legal obligation to render such payment,it cannot be seen as consideration in the legal sense。
再问： and which one is correct？