Final answer:
The most effective and persuasive conclusion for the commercial script provided is option B) Planning a birthday party is a piece of cake with The Cake Place.
Step-by-step explanation:
The most effective and persuasive conclusion for the commercial script provided is option B) Planning a birthday party is a piece of cake with The Cake Place. This conclusion uses a catchy phrase and plays on the word 'cake' to make it memorable and engaging. It also presents The Cake Place as the perfect solution for planning a birthday party effortlessly, emphasizing convenience and expertise.