Question

why are multiple species of primary producers needed for a robust ecosystem?
a) a single species cannot produce enough biomass for consumers
b) a change in one environmental factor could threaten the ecosystem
c) a single species cannot supply enough nutrients for consumers
d) a single species cannot be consumed by several other species

Explanation:

Biodiversity in primary producers provides stability. A single - species dominance makes an ecosystem vulnerable to environmental changes like climate, pests, or diseases. Multiple species can better withstand such changes.

Answer:

b) A change in one environmental factor could threaten the ecosystem