Final answer:
The pivotal factor for a message to persuade is that the audience needs to be paying attention. Attention allows the audience to process the message deeply through the central route of persuasion, which is vital for attitude change.
Step-by-step explanation:
The crucial step that must take place before a message is likely to persuade is that b) The audience must be paying attention. Without the attention of the audience, it is unlikely that the message will be processed deeply enough to persuade anyone. According to the Elaboration Likelihood Model of persuasion, the features of the source, the content of the message, and the characteristics of the audience all play a significant role in whether attitude change will occur. For the central route to persuasion to be effective, which involves the audience engaging in a deeper processing of the information, the audience needs to be analytical and motivated to consider the message.
On the contrary, peripheral route persuasion relies on cues such as celebrity endorsement and positive emotions, but notably, not on factual information. Therefore, for any persuasive message to be successful, it's vital for the audience to give their attention to it.