Why is it necessary to have a balanced environment ?

Survival of all organisms is actualized due to ecological balance. Various species survive because favorable ecosystems were created. Favorable ecosystem ensures that each organism thrive and multiply as expected. They get enough food to keep them alive. Ecological balance is also important because it leads to the continuous existence of the organisms

because they are eaten by the frog and the frog getseaten by the snake and the snake by the eagle

i believe your answer would be c.. : )