Answer:
A
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Explanation:
Sunlight provides energy needed for photosynthesis
A- when the atoms covalently bond, the two hydrogens share an electron with the oxygen. As a result, they both acquire the ‘noble gas’ rank of having a full out energy shell (8 valence electrons).
Bacteria, pollen, and transplanted tissue are examples of Foreign antigens.
- The source of foreign antigens is external to the body. Examples include components of or compounds created by viruses, microorganisms (such as bacteria and protozoa), substances in snake venom, specific proteins in meals, pollens and serum and red blood cell components from other people.
- T cells only identify foreign antigens that are present on the surfaces of the body's own cells, as opposed to immunoglobulins, which interact with infections and their harmful products in the extracellular spaces of the body.
- These antigens may come from pathogens that proliferate inside of cells, such as viruses or intracellular bacteria, or they may come from pathogens or their byproducts that cells have ingested through the process of endocytosis.
learn more about Foreign antigens here: brainly.com/question/18081324
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