Final answer:
Without additional context, it is uncertain how increasing soccer ball production would affect volleyball output as it depends on factors like shared resources and market demands.
Step-by-step explanation:
The question is asking how an increase in the production of soccer balls might affect the production of volleyballs. The closest answer related to this question might be 'D. Uncertain' because the effect on volleyball output depends on multiple factors such as the production capacity of the factory, whether the same resources and equipment are needed for both products, and how the market demand for both products interacts. Without additional context, it is impossible to determine with certainty whether producing more soccer balls would increase, decrease, or have no effect on volleyball production.