"S (seller) sold his TV set to B (buyer) who gave S the option to deliver instead of his refrigerator. Is S liable to B in case the TV is lost through S's fault?"

My answer is no since B already gave S the option. What I do not understand is what is the purpose of a refrigerator and what article is this? I am also not sure of my answer and am still figuring out how to understand and study obligations and contracts please forgive my ignorance in the subject.