Which of the following is a non-verbal element of speech delivery?

Body language is a crucial non-verbal element of speech delivery. It encompasses various forms of communication outside of spoken or written words, including gestures, facial expressions, posture, and eye contact. These non-verbal cues can significantly enhance or detract from the message being conveyed. They help to express emotions, emphasize points, and engage the audience, making them vital for effective communication.

In contrast, grammar usage, complex vocabulary, and script length fall under verbal elements of speech. Grammar usage pertains to the structure of sentences and how ideas are expressed, while complex vocabulary involves word choice and language sophistication. Script length refers to the duration or amount of content, which also does not pertain to non-verbal communication methods. Therefore, body language stands out as the correct answer, as it directly relates to how a speaker presents themselves beyond just their words.