Answer:
C. The populations of all other organisms in the food web would decrease because there would be less energy.
Step-by-step explanation:
In the Arctic ecosystem, phytoplankton is producers which synthesise food with the help of sunlight. In this ecosystem, zooplankton and krill are primary consumers as they feed on phytoplankton.
Arctic cod and bowhead whale are secondary consumers which feed on primary consumers. In the arctic ecosystem, the temperature is rising which is killing the phytoplankton.
If the phytoplankton population decreased, then all the consumers in the food chain in this ecosystem would decrease due to lack of food.