Ответ: a) The pond and its inhabitants constitute an ecosystem
b) When humans or natural disasters alter the ecosystem, plants and animals can be threatened with extinction
c) Various events can change the balance of the ecosystem.
d) The pond is a habitat. The pond and its inhabitants constitute an ecosystem. All the inhabitants of the pond constitute a pond community. This is the ecosystem
e) Yes, if people do not litter, then the ecosystem can be changed for the better and there will be no threats.
f) natural disasters also upset the balance in the environment