Answer:
A. It would decrease.
Explanation:
If the producer population is decreased in an ecosystem then this would have a negative impact on the herbivore population.
The population of herbivore would decline as the herbivores are the organism that feeds on the green plant to obtain nutrition and energy, the producers in the ecosystem are most commonly the green plants and hence, if the producers are removed then the herbivores that depend on them for obtaining nutrition and energy would eventually die and their population would decrease.
