Question 3(Multiple Choice Worth 5 points) (07.06 MC)
Which of the following best describes an example of a specific internal response to harmful bacteria?
Skin serves as a physical barrier that prevents bacteria from entering the body.
Saliva contains enzymes that destroy bacteria and prevent infection.
Bacterial infection causes the release of histamine, which leads to inflammation and swelling.
Antigens trigger the production of antibodies, which mark bacteria for destruction.

A the skin is the bodies first line of defense

Explanation:

The first line of defence is non-specific and aims to stop microbes from entering the body. 

Antigens trigger the production of antibodies, which mark bacteria for destruction.

Explanation:

The question is talking about internal response to bacteria so we have to look at what happens inside the body pertaining to bacterial infection, so the answer is "Antigens trigger the production of antibodies, which mark bacteria for destruction".

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.