Sentence 1: Beatrice heard whimpering outside her front door. 
 Sentence 3: A little white dog sat on her doorstep 
 Sentence 4:  Beatrice found the dog's owner's phone number on its tags 
 Sentence 5:  She called the owner and told him she found the dog 
 Option 1: She opened the door to see the cat outside. 
 Option 2: She opened the door to see what was outside.