4)

background: the u. s. marine corps first adopted a blm wild horse for the mounted color guard in 1988. a two-year old horse called "okinawa" became an integral part of the equine unit, quickly learning to lead a parade with flags flapping, jets flying overhead, audiences clapping and dealing with unexpected loud noises. (2) his calm performances encouraged the marines to adopt seven other wild horses. (3) the mounted color guard has since participated in every tournament of roses parade in pasadena, california, since 1990, as well as dozens of other annual parades and shows.

which is the least effective substitution for the word ’calm’ in the sentence labeled (2)?

a) composed
b) quiet
c) tranquil
d) unruffled