Final answer:
The correct answer is option c. The eye normally takes in at each fixation point 7-9 letters to the right and 3-4 letters to the left, connected to how visual acuity is affected by factors like the pupil's diffraction and the size of rod and cone cells.
Step-by-step explanation:
The number of letters the eye normally takes in at each fixation point before moving on to the next fixation point is c. 7-9 to the right and 3-4 to the left. The details of our visual acuity and perception are connected to the biological and physical aspects of our eyes.
For example, diffraction by the pupil can affect visual acuity. A simple experiment demonstrates that when you focus on an object, disparity in depth causes objects at different distances to appear at various points of each retina.
The power of our eye, measured in diopters, along with the size of rod and cone cells, determines our ability to resolve fine details such as letters on a page. This ability is what allows for a particular number of letters to be processed per fixation when reading.