The correct answer is:
c. The age range of the readers
Whenever you want to write about something the first question you have to ask is for whom is this directed to. You should do an Audience Analysis. An Audience Analysis is the process of gathering information about the people in your audience so that you can understand their needs, expectations, beliefs, values, attitudes, and likely opinions. Whenever you analyze the age of your audience, you can choose a topic that most of them will like and agree.