Answer:The correct answer is B. Organum. I hope this helps you
Step-by-step explanation
Organum is a term applied to medieval music that consists of Gregorian chant and one or more additional melodic lines.
Organum is a type of medieval music that features Gregorian chant and one or more additional melodic lines. This polyphonic style of music was especially popular in the 12th and 13th centuries, and it is considered a precursor to modern Western harmony. Organum developed as composers sought to add complexity and interest to the simple chants of the Church by introducing new melodies and harmonies. The result was a rich and intricate style of music that laid the foundation for much of the Western classical tradition.