I believe the correct response is A. The population of secondary consumers would decrease, as now these organisms can't obtain energy through the food they consume which is the primary consumers as there is none and thus the population in higher tropic level dependent on them would decrease. This is the secondary consumer.
Explanation:
Mutualism is defined as an interaction between individuals of different species that results in positive (beneficial) effects on per capita reproduction and/or survival of the interacting populations.
A because yeast do alcholic fermatation in bread when you bake and some bacterias prokayotes live off it.
