Two subgroups of a population separated by a river are rejoined when a drought causes the river to run dry. Assuming that speciation has not yet
occurred, what is true about the two subgroups?
A. Speciation will not occur if individuals in different subgroups can
freely mate and have fertile offspring.
B. The two subgroups will still be reproductively isolated and unable
to mate.
C. New traits that resulted from mutation will not flow between the
subgroups.
D. Speciation will speed up since there will be more competition
between the subgroups

the answer is 1. photosynthesis. glad to

yes it is   dangerous

explanation:

because that foot is discusting and could get you sick

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".

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.