For Part A, the central idea of "Barbie Is in Her 60s and Still Going Strong!" is:
Barbie provides inspiration to girls by reflecting different identities.
For Part B, the quotation that best reflects the development of the central idea in Part A is:
"The first African American Barbie doll hit store shelves in 1968."
This quotation exemplifies how Barbie has evolved to represent diversity and inspire girls from various backgrounds.