Final answer:
The net primary production would decrease if biodiversity decreases in an ecosystem due to natural or man-made disturbances.
Step-by-step explanation:
The answer to the question is b) Decrease. When biodiversity decreases in an ecosystem due to natural or man-made disturbances, the net primary production also decreases. This is because biodiversity is directly related to the number and variety of primary producers (plants) in the ecosystem. When biodiversity decreases, there are fewer primary producers available, leading to a decrease in net primary production.