The correct option is A.
The observation that the embryos of certain species have physical and genetical similarities in the earliest stages of embryonic development shows that individual development of an organism shows its revolutionary history and this is taken as an evidence of common ancestry. Scientists takes this observation to mean that all life on earth developed from a single ancestor.<span />
The ability of a cell or a body to fight against the infection is called immunity. The T cell and B cell helps the body to fight against the infection.
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What are T cells?</h3>
T cell is also called as T lymphocyte, it is also a important part of immune system. T cell originate in the bone marrow and mature into the thymus.
There are three types of T cells:
- T helper cell
- T killer cells
- T cytotoxic cells.
Helper T cells secrete chemical messengers called cytokines. Regulatory T cells helps to control immune reactions. They are released into blood streams.
Therefore, The ability of a cell or a body to fight against the infection is called immunity. The T cell and B cell helps the body to fight against the infection.
To learn more about T cells, refer to the link:
brainly.com/question/1434048
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Reason why people leave certain locations is
B. Push factors
The answers would be histones; nucleosomes.
Sentence form: In the nucleus, DNA is wrapped around histones to form nucleosomes.
