Answer: It shows how determined Elion was to learn more about biochemistry.
Explanation: The main idea seems to be that Elion had to struggle to advance in her career. When she could not immediately get into grad school, she took opportunities that were related to her interests and would help her to learn more about biochemistry until she could earn her master's degree.
The last two answers may also be true, but the question is about the support for the main idea in this paragraph