Researchers who study the process of reading in children have discovered that better readers make smoother eye movements across the page (e. g., there is a positive correlation between reading skill and the smoothness of the eye movements). which of the following is a possible cause of this correlation between smooth eye movements and reading ability?

a. all of these options are possible causes of the correlation.
b. having good reading skill allows a child to make smooth eye movements.
c. some third factor might cause both smooth eye movements and improved reading ability.
d. the ability to make smooth eye movements improves reading ability.