Final answer:
If a strong A story theme supports the main show theme, the B and C stories should complement this theme, adding depth and contributing to the overall story arc.
Step-by-step explanation:
If you have a strong A story theme that supports your show theme, the B and C story should also relate to the show theme. This means that these subplots are not eliminated nor do they become the focus; they serve to enhance the main theme and add depth to the show.
Secondly, while the B and C stories should complement the A story, they do not become completely independent from it. An effective narrative uses its subplots to contribute to the overall story arc, including character development and thematic exploration.