Geologists determine absolute age by comparing the amounts of radioactive and nonradioactive elements in rock. The radioactive, or
, elements decay into nonradioactive elements. Because this rate of decay is
for each element, geologists can compare the amounts of stable and unstable elements to determine how much of the
elements have formed over time.

climate change and pollution

that is wrong, its not thymus.

the glands which are associated with each description is given below:

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.