The answer is B. Keyword being "theory of radioactivity" and "influential scientists of the century." It's a persuasive keyword that will hook the readers. What is theory of radioactivity? How did her theory garner her the title of influential scientist of the century?
Choice A is vague and hardly persuasive. It's only characterizing her traits: curious and determined.
According to grammar rules and most style books, you would hyphenate all compound numbers from twenty-one to ninety-nine. Therefore the correct answer is b, ninety-eight.
Answer: Because if you are uncertain of what's happening then you don't know how to deal with the situation. So in order to compensate for that not knowing, you take a risk.
