Sentence 1: Rich came home from vacation and was horrified. 
 Sentence 3: He wandered around, looking for the source of the smell 
 Sentence 4:  He found a gallon of sour milk on the table 
 Sentence 5:  Rich opened windows to dissipate the smell 
 Option 1: His house had caught fire while he was gone. 
 Option 2: For some reason, his house smelled really bad!