The large number of antibodies that can be produced in a single individual is a result of a single b cell: producing multiple unique antibodies by genomic rearrangement. being able to produce unique antibodies from both the maternal and paternal alleles. producing a unique antibody from all other b cells by genomic rearrangement. secreting multiple antibodies that will be presented on the surface of other b cells.

The answer is; producing a unique antibody from all other B cells by genomic rearrangement.

An isolated B cell produces monoclonal antibodies (also called Immunoglobulins). Different B cell types produce different types of antibodies (hence the serum of an animal has polyclonal antibodies). Memory B cells are developed when a particular infection is eradicated by the immune system. These B cells proliferate when the infection returns by producing the same antibodies that were effective against the foreign entity.

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these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.