What causes a drop in female hormone levels? a: the onset of the menstrual flow. b: if an egg is released from the ovary. c: if the uterine wall thickens. d: if the egg is not fertilized.

Ans. (D). if the egg is not fertilized.

The major female sex hormones (estrogen and progesterone) are released by ovaries. During ovulation, ovary releases female gametes or eggs. After the release of eggs, corpus luteum is formed in the ovary, which releases both the female hormones (estrogen and progesterone) and prepare uterine lining for potential pregnancy.

When fertilization occurs, corpus luteum continuously secrets female hormones and allows implantation. However, if the egg is not fertilized, the corpus luteum starts to degenerate and secretion of female hormones stops.

Thus, the correct answer is option (D).

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.