The diploid cells in the testes that undergo meiosis i to produce haploid cells are the
a. secondary spermatocytes
b. primary spermatocytes
c. interstitial cells
d. spermatogonia
e. sertoli cells

b. Primary spermatocytes

Explanation:

Primary spermatocytes are the diploid cells present in seminiferous tubules of testes. These diploid cells enter meiosis I and produce haploid cells. Each diploid primary spermatocyte produces two haploid cells by meiosis I which are called secondary spermatocytes.  

The secondary spermatocytes then enter meiosis II to produce sperms.  

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i guess you forgot putting it.

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.