Which one is it out of all?

google says it means "not showing due respect for another person" so i would say the last one "rude and disrespectful"

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.

what does the teacher mean