A they reveal what the adolescents of this generation are like and what they value.
B they will expose that teenagers from the early 21stcentury could not use the web for research.
C the children will be adults in the next century and their past habits will not interest historians.
D the content of the web pages has lasted for many centuries, so it is correct to use the expression.
E the early 21stcentury kids research about journeys to past eras and learn historical events in general.