Sentence 1: Kathy had just had a new baby. 
 Sentence 3: When she answered the door she saw her friend 
 Sentence 4:  They were holding a casserole dish 
 Sentence 5:  Kathy thanked her friend for bringing her food 
 Option 1: She was home with him when the phone rang. 
 Option 2: She was home with him when the doorbell rang.