Read the excerpt below. Which of the following statements best summarizes the main idea of the excerpt?
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.

a. Elion was never able to earn a doctorate degree even though she was brilliant.
b. After waiting for years, Elion finally earned her master's degree in 1941.
c. Elion was determined to do everything she could in order to practice chemistry.
d. Elion was angry that she could not have a research position because she was a woman.