Boethius wrote of
or the music of the universe.
a. musica universalis
o
b. musica mundana

o
c. musica humana
d. musica instrumentalis

The answer is B: musica mundana

Explanation:

It's important to know that Boethius (full name: Anicius Manlius Severinus Boëthius) was a Roman politician (consul), poet and philosopher who lived in the 1st century AD.  As a member of the school of Neoplatonism, he strongly backed the opinion that art and science are inseparable.  De Musica is the name of his famous work where he introduced the first hierarchy of the music: Musica mundana, Musica humana, and Musica instrumentalis.