What was guido d'arezzo's contribution to musical notation? a. hexachords b. staff lines c. rhythm d. articulation marks e. neumes

The answer is : staff lines. He devised an arrangement of lines and spaces that developed into the musical staff. Two of Guido D'Arezzo's primary contributions to music history : 1. developed a 4-line staff circa. 1025 2. wrote a text on music ca. 1026 called "Micrologus"

staff lines

Explanation:

its the answer for apex

a chromatic scale uses the twelve tones of the octave, while a regular scale only uses eight, or seven different notes (as the first note is played twice)

i think it's but if you get it wrong its not my fault : )