The earliest form of musical notation, such as that of Guido d'Arezzo, indicated pitch only, because the

The earliest form of musical notation can be found in a cuneiform tablet that was created at Nippur, in Babylonia (today's Iraq), in about 1400 BC

the right answer is 6

either online or traditional classroom can work for students. which is better will depend on students and teacher. students may have trouble following a lesson in classroom while they can study at their own pace online. other students may have trouble staying focus on their own in online classes. teachers are more used to classroom teaching but they may also be more worry about their jobs teaching online classes and work harder.