Answer:
Sickle cell anemia.
Explanation:
Pleiotropy may be defined the gene that shows multiple effects in the organisms. Pleiotropic gene doe not follow the Medndel's law of heredity completely.
The sickle cell anemia is caused by missense mutation in which glutamic acid is replaced by valine. This is only affected by the single gene and do not show multiple effects. All the other traits mentioned in the question are the examples of pleiotropy.
Thus, the correct answer is option (A).
