Answer:
a. antigen
Explanation:
The Immune system is composed of immune cells that defend the body against foreign substances such as bacteria or virus. Lymphocytes (B and T cells) are one of the main immune cells
Lymphocytes have the ability to recognize and bind to antigens, wich are substances foreign to the body ( i.e bacterial or virus elements) that evokes an immune response.
<span>The building blocks for lipids are three fatty molecules and one glycerol molecule.They join to form a simple fat, or triglyceride. Proteins building blocks are amino acids. Amino acids are small molecules that contain carbon, hydrogen oxygen, and nitrogen atoms. Nucleic acids building blocks are nucleotides which are connected to form long chains,</span>
The answer is “The Nervous System”
Answer: petroleum
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