Teacher to a student: You agree that it is bad to break promises. But when we speak to each other we all make an implicit promise to tell the truth, and lying is the breaking of that promise. So even if you promised Jeanne that you would tell me she is home sick, you should not tell me that, if you know that she is well. Which one of the following is an assumption on which the teacher's argument depends? ['One should never break a promise.', "It is sometimes better to act in a friend's best interests than to keep a promise to that friend.", 'Some implicit promises are worse to break than some explicit ones.', 'Breaking a promise leads to worse consequences than does telling a lie.']