Answer:
Has Toni made a good decision?
C. Maybe, but she should think about other characteristics of the audience, too.
Explanation:
Toni's decision is not exactly wrong. We can actually say it is a bit too safe. She has chosen a topic that is indeed related to health and that might be seen as interesting by people who study anything that is also related to health. However, she should consider her audience a bit more deeply. Perhaps she could talk to some people in order to come up with a topic that is more useful, or even more entertaining. As a matter of fact, the history of the discovery of DNA is something that most of them are likely to know already.