Answer:
addition of a second melodic line to Gregorian chant
Explanation:
The developments in society and religious domination are some of the inclinations of Western music during the Medieval times. The most flourishing music during those times was sacred music. The domination of the Christian religion and church music gradually took the form of Gregorian Chant. The monophonic melody of Christian music later developed to polyphonic music. Pope Gregory, I is associated with the establishment of the change in the music. It is because of this reason, the shift in the music has been known as Gregorian Chant.
A major triad can be created with 3 notes, by starting with a note, like “C” then adding a note a major 3rd higher, “E” which is four half-steps, then on top of that, adding a minor third (3 half steps up), above that G. C-E-G
A major third can start on any notes, using the same formula of major third and a minor third
D-F#-A, Bb-D-F
Eb-G-Bb.....