Under the CISG, an offer becomes effective when:

Group of answer choices

sent by the offeror; it may be withdrawn any time, but only in writing

received by the offeree; it may be withdrawn any time before acceptance is communicated

received by the offeree; it may be withdrawn any time after 30 days

sent by the offeror; it may be withdrawn any time before acceptance is communicated

sent by the offeror; it may be withdrawn any time after 30 days