Answer:
When you want to know how many students are talking online with their friends, The first thing that will come into mind is
1. Whether they Possess computer at home or not
2.Secondly, If they don't have Personal computer at home is their parents give them enough money to learn Surfing, chatting and be well versed with internet in cafe room or in computer classes, apart from school.
As we can also say that, students who own the latest computer technology may not be interested in talking to their friends online.
So, Option D Appears correct:Randomly selected students from the school attendance list.