Which One Is the Correct Reaction Sequence for the Attachment

Which one is the correct reaction sequence for the attachment of valine on the N-terminus of a growing peptide?

A) Amino group deprotection,addition of Val and base,heating.
B) Amino group cleavage on Val,activation of carboxylic acid functionality on growing peptide chain,reaction between the two.
C) Amino group protection on the growing peptide chain,activation of the carboxylic acid functionality on Val,reaction with growing peptide.
D) Amino group deprotection on growing peptide,activation of the carboxylic acid functionality on Val,reaction with growing peptide.
E) Mix Val and growing peptide,add base and incubate the two for a period of time.