What has happened to the enrollment of students in the 20 through 21 age group over the time period?

Someone answer this check out the image!

Ascientist wants to use a model to present the results of his detailed scientific investigation. why would a model be useful? a )because the model makes the concepts easier to understand b) because the model is easy to put together and to use c) because the model prevents other scientists from asking questions d) because the model requires the audience to pay full attention to it i don't know what to choose because between a and d a is much more likely than d because it only wants to get the attention of the audience. i'm confuse.

Select the graph of the solution. click until the correct graph appears. |x| = 3