Answer: 1. Facts and statistics.
Explanation: An argumentative speech is a speech with the main function of persuade the audience (readers or listeners), it tries to change their points of view usually on a controversial issue. In this case, the given sentence tries to convince the audience of the positive influence of publicity in orchestra enrollment, but it is needed to present facts and statistics to support that argument and make it more believable to the audience, for example, statistics that show which percentage of the orchestra enrollment was in fact produced by the publicity.
