Answer: b. To persuade.
Step-by-step explanation: A persuasive speech is a specific type of speech in which the speaker has a goal of convincing the audience to accept his or her point of view or opinion, usually about a controversial topic. In order to achieve this goal, the speaker uses rhetorical devices to produce an effect in the audience and try to convince them. If a speech addresses the importance of changing the legal voting age it is a persuasive speech.