Chemical synthesis of peptides by the Merrifield method:. a. has a practical upper limit of a polymer of about 500 amino acid residues.
b. involves synthesizing the peptide and then attaching it to a solid support.
c. is nearly as efficient as peptide bond synthesis in biochemical systems.
d. proceeds from the carboxyl terminus to the amino terminus.

b. involves synthesizing the peptide and then attaching it to a solid support

the amino acid is reacted with a molecule known as a "linkage agent" that enables it to attach to a solid polymer, and the other end of the linkage agent is reacted with the polymer support (insoluble)

it is b

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