Read the following paragraph. How does sentence 3 develop the main idea of the paragraph?

Gertrude Belle Elion was born on Jan. 23, 1918, in New York City.
She graduated from Hunter College in New York City with a degree in biochemistry in 1937.
Unable to obtain a graduate research position because she was a woman, she took a series of jobs, including lab assistant, chemistry and physics teacher in New York City high schools, and research chemist.
During this time she also took classes at New York University, where she earned a master's degree in 1941.
Because she could not devote herself to full-time studies, Elion never received a doctorate.
It shows how determined Elion was to learn more about biochemistry.
It supports the idea that Elion could not get accepted into colleges.
It shows how her different jobs helped her to be a better chemist.
It supports the idea that women can be very determined.