Stable ecosystems can be altered, either rapidly or slowly, through which of the following events?

Stable ecosystems can be altered, either rapidly or slowly, through human activities, natural disasters, climatic changes. An ecosystem may be described as a community and its surrounding which includes non living organisms. Human activities such as deforestation, mining, dumping of wastes on the oceans alters and affects the ecosystem  negatively and thus making the habitats unfavorable for the organisms. Natural disasters such as floods, tsunami  and climatic changes may also alter the ecosystem.

The correct answer to this question would be c