Over the last four months, the number of building blocks sold to parents of preschoolers increased. During the same time period, the number of educational videos sold increased as well. Which of the following would be a valid conclusion?
A.
There are more parents with preschoolers than there are parents with children of other ages.

B.
Educational videos were purchased to be used with the building blocks.

C.
Building blocks were purchased to be used with the educational videos.

D.
The sales of building blocks and educational videos are not related; therefore there is no correlation.