Sentence 1: Susan was happy because it was her birthday. 
 Sentence 3: When she got to her home, all of her friends were waiting 
 Sentence 4:  They planned a big party 
 Sentence 5:  It was the best birthday Susan ever had 
 Option 1: She was on her way home from work whistling. 
 Option 2: She was on her way to her friend's house for a big party.