Sentence 1: Becky wanted to impress her pals. 
 Sentence 3: When her pals begged, Becky let them each keep a rock 
 Sentence 4:  The pals left, and Becky looked at the empty spaces in the collection 
 Sentence 5:  She walked along the road picking up rocks to fill the spaces 
 Option 1: She showed them her dad's prized collection of rocks. 
 Option 2: She showed them her dad's prized collection of bugs.