Final answer:
Impromptu speaking refers to a presentation delivered without prior notes or notice. The speaker's delivery and audience engagement play critical roles in the success of a speech, not just the content or structured script writing.
Step-by-step explanation:
Impromptu speaking refers to a presentation c) delivered by the speaker without notes and without advance notice. In impromptu speaking, the ability to think on your feet and articulate your thoughts coherently and effectively is essential. This type of speaking contrasts with presentations that are memorized in advance or supported by notes or cue cards. In the context of a speech, being prepared to speak impromptu can be an invaluable skill. As for developing a successful speaking event, the true measure of success often lies not just in the content or structure, but also significantly in the speaker's delivery and ability to engage the audience. Whether it's a classroom assignment, a professional presentation, or a social media video, the base principles of script writing and delivery are fundamental to achieving a memorable and effective speech.