Which statement associated with mosquito helps understand that malaria is a communicable disease?
(a) The causative agent of malaria is a protozoan.
(b) The mosquito carriers the parasite Plasmodium that causes malaria.
(c) The mosquito lays its eggs in water collected in tyres, coolers, and open pits.
(d) The parasite is transferred inside the body of a health person along with the
mosquito bite.

(d) The parasite is transferred inside the body of a healthy person along with the mosquito bite.

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.