I need help with this question

A big and young population strains the food supply and the economy. As the youthful population matures, fewer employment will be available for succeeding populations.

here is the correct answer.

i got it wrong but it showed me the correct answer.

the correct answer is - c) the ecosystem would be unable to recover after any event.

if in a certain ecosystem, lot of new species of plants and animals are introduced, and those plants and animals can survive in those conditions, than the ecosystem will experience dramatic changes and would never be the same again.

the new species, which will practically be invasive species, will start to compete with the native ones, and very often the invasive species come as tougher. the ecosystem will start to rapidly change, the native species will have much more competition and their numbers will dwindle, and in no time the whole ecosystem will be unrecognizable.