The sun set behind the hills, is the verb transitive or intransitive?

Choose the sentence that is not logically connected in the paragraph. (1) it all happened late one night after the family had gone to bed. (2) jack was lying in bed when he remembered he had left the groceries on the back seat of the car. in the paper bag was a carton of ice cream. (3) the ice cream would melt during the warm summer night. (4) he put it in the refrigerator.