Read this script for a television advertisement. Which sentence is an effective and persuasive conclusion for this script?

A) Volunteers will need to be available one weekend a month to work.
B) Although volunteers are unpaid, volunteering is still a good use of your time.
C) Volunteering at the garden is a great opportunity to get outside and meet new people!
D) Working in the city garden will give you the knowledge you need to plant your own vegetables.