Students who respond promptly to e-mails are following which netiquette rule?

keeping content appropriate

assessing an online environment

respecting everyone's time

practicing ethical behaviors

C) Respecting everyone's time (I think)

Explanation:

C) Respecting everyone's time (I think)

It can't be the first 2 because we don't know what's in the e-mail. I think it's the 3rd one because some people don't have the time to wait for you to ponder about the email for about a millennia. Also, it's polite.