Sentence 1: Mike and his wife were afraid their cat would scare their baby. 
 Sentence 3: One day, Mike forgot to close the door 
 Sentence 4:  The cat walked in the open door 
 Sentence 5:  The cat curled up happily under the baby's crib 
 Option 1: They decided to give the cat to a close friend. 
 Option 2: For a long time, they kept the cat out of the baby's bedroom.