Human beings are part of earth's ecosystems. thus, human activities can, deliberately or unintentionally, alter the equilibrium in ecosystems.

humans often change ecosystems as a result of population growth, consumption, and technology. which of the following exemplifies a way in which humans modify ecosystems?

cutting down trees to build new buildings and roads
factory and automotive emissions causing acid rain
redirecting and storing freshwater behind dams
all of these

Its all of these

Explanation:

im coming from study island haha

estuaries are the partially enclosed coastal bodies of brackish water formed at the mouth of sea where river meets an ocean. it is a transition zone between river and sea water so estuaries are influenced to both marine environment such as tides, waves and to riverine such as flow of fresh water and sediments. the mixing of sea and fresh water provide high level of nutrients, making estuaries a high product habitats.

many estuaries suffers degradation from a variety of human activities like erosion from deforestation, overgrazing, overfishing, drainage and eutrophication.

so from the above statement answers will be

1. false as estuaries are formed due to both brackish and freshwater.

2.true, due to high productivity estuaries are breeding ground for many marine species.

3. direct and indirect activities of man that contribute to pollution and deposition of sediments.