What are the three principal classes of musical instruments?

Look at this painting by cimabue. this painting demonstrates the use of

In 1401 a competition to create a set of bronze doors for the baptistery of florence cathedral was held, and this competition is often credited with the beginning of renaissance art t or f?

Blind contour line drawings are : a. often used to paint landscapes b. often detailed but not perfect c. often detailed and flawless