70 year old emmetrope is used as a subject in a spherical... Help with optometry question please?

70 year old emmetrope is used as a subject in a spherical ametropia simulation experiment. Which of the following statements is true?
Choose one answer.
a. Vision falls when both positive and negative trial case lenses are added
b. Vision falls only when myopia is simulated with positive lenses
c. Vision doesn't change with the addition of positive and negative lenses
d. Vision only gets worse when adding negative lenses

Thank you!
Answers:   D...

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