What is the main purpose of the paragraph that begins with, "On becoming an astronaut:" in "Eileen Collins—NASA's First Female Shuttle Commander to Lead Next Shuttle Mission"?

A: to make the argument that there should be more female shuttle commanders in the NASA program

B: to inform readers about the Mercury astronauts and what they accomplished in space

C: to explain how opportunities for women in aviation helped pave the way for women to join the space program

D: to convince young people to pursue careers in space travel