The answer is b it occurs in plant animals and bacteria
Answer:
Oxygen.
Explanation:
Yeah no thats' all there is to it...
The number of covalent bond an element can form depends on the number of electrons it has in its outermost shell (valence electrons). Carbon has four valence electrons, therefore, it can form maximum of four covalent bonds in an organic compound.
The formation of new viruses.
Memory B cells are the type of B cells which are formed after the primary infection.
These are important as they help in producing the more intense and accelerated immune response during secondary infection or when the same antigen or infectious agent enters the body.
They do so by producing the polyclonal response, that is, the same epitope is attacked by multiple copies of B cells.
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