Answer:
C, persuasive essay
Step-by-step explanation:
The question is asking you to convince readers to get more exercise, so you need an essay to convince, or persuade the reader.
An expository essay is when you are given an idea to explore, read passages to find evidence, and write about that topic.
An informal personal essay is a nonfictional story about personal experiences or story, up to the author.
A persuasive essay is used to convince the reader to do something, and can be effective or not effective.
A formal personal essay is the same thing as an informal personal essay, except it's more based on real life situations, or evidence from articles.
Option C would be the correct answer for this question.