Q.

Which of the following would be affected by the decrease in the producer population

1 All the organisms in the ecosystem.  
2 The organisms in the next trophic level.  
3 The organisms at the highest trophic level.  
4 None of the organisms in the food chain will be affected.  

Ans.

(1)

A decrease in the population of producers would directly and indirectly affect all the organisms in that ecosystem.