Which of the following statements about the basic structural features of dna are true? select all true statements. select all true statements. the twisting of the dna double helix is attributed to the tight packing of dna bases and base-stacking. the major and minor grooves prevent dna binding proteins from making contact with nucleotides. the major and minor grooves form in the dna helix because the dna strands are antiparallel. in a dna macromolecule, the two strands are complementary and antiparallel.

the answer for this question would be d. glaciers

the question isn't complete here so i can't right an answer '_'

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.