Giraffes with short necks lived in arid regions and fed on grasses. Over time, grasses disappeared, forcing giraffes to eat from trees. Mutations in the genome led to some giraffes inheriting the trait for long necks. Over time, there were more giraffes with long necks in the region. What are the two reasons for the change in the population of giraffes?

adaptation
artificial selection
natural selection
analogous structures

the tricuspid valve is present between right atrium and right ventricle

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.

synapse nervous system

your answer is going to be physical weathering