A stem cell is: A. a specialized cell that can divided limitlessly
B. a specialized cell that can divide limitlessly but can't differentiate
C. an unspecialized cell that can't divide limitlessly nor differentiate into specialized cells
D. an unspecialized cell that can divide limitlessly and differentiate into specialized cells

A stem cell is A. a specialized cell that can divided limitlessly

Explanation:

sorry if i keep answering ur questions im j good at this stuff lol

the correct answer is option b

behavioral response need communication and thus co-ordination at several levels such as interaction among cells, organ system and the entire organism.

behavioral response produces both internal and environmental stimulus.

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.