The most reliable source for a presentation about education in multi-age classes would be
a. school textbook for students.
b. parenting blog about student mentors.
c. wiki website about the history of one-room schoolhouses.
d. journal article about classrooms with students of varying ages.

The most reliable source for a presentation about education in multi-age classes would be a D. journal article about classrooms with students of varying ages. If you need to make a presentation about multi-age classes, then you should definitely check out that article given that it talks about learners of different ages who are still studying. You can see the ways in which they learn and compare it according to their ages. This article is the best option among these because it covers a lot of ages, isntead of just one.