1) As a child, Barbara tired of playing with baby dolls. (2) At this time, there were no adult-looking dolls on the market. (3) The famous Barbie doll was named after the child of Mattel cofounder Ruth Handler. (4) Ruth decided to make a grown-up doll that would allow Barbara to envision her future. (5) Mattel unveiled the Barbie doll at the 1959 American Toy Fair in New York City. (6) Barbie soon became the most popular doll in the United States. Which sentence in this paragraph would work best as the introductory sentence?