What is the role of cyclin-dependent kinases in the cell cycle?
question 5 options:

they stop the cycle if something has gone wrong.

they catalyze the condensation of the chromosomes.

they provide the energy for the actions of the spindle fibers.

they initiate various stages of the cell cycle.

it is either c or d and i know for sure it is not a or b

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.