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

The least effective substitution from the given options is quiet, due to its simple meaning about the intention of the full sentence "His calm performances encouraged the Marines to adopt seven other wild horses." this sentence talks about the general behavior of the horse and quiet mostly refers to the noise that is produced, while the other has a wider use depending on the context.