C) Volunteering at the garden is a great opportunity to get outside and meet new people!
Explanation:
This sentence is the one that most resembles an effective and persuasive conclusion for the script. Because the conclusion comes at the end of the text, it should not introduce any new information. Instead, it should give an idea of closure. This sentence does not introduce any new piece of information. Moreover, it indicates to the reader that the text is over. Finally, it ends by providing a positive statement, which is likely to increase the persuasiveness of the text.
