I found the options to the exercise on the internet. Here are they:
"A. A defect in a single gene causes a disease in which affected individuals have longer limbs.
B. A defect in a single gene causes a disease in which affected individuals have longer limbs and vision problems.
C. A single gene determines whether or not an individual is colour blind.
D. A single gene determines the hair and eye colour of an individual.
E. Multiple genes determine the height of an individual."
The scenario B is the one that best describes a pleiotropy. Pleiotropy is the phenomenon that is present when a single gene influences the phenotype of two or more different traits that have no direct relation. A and C scenarios are one gene-one characteristic. E scenario is multiple genes-multiple characteristics. D scenario although it shows a gene being related with two different "organs", both traits are easy to relate as the base of it is coloured pigmentation in cells.