Mendelian genetics question.

Sickly cell anemia is a disease whose phenotype includes not only anemia, but damage to many different organs. All phenotypes, however, can be traced to a single gene. This is an example of
A. mulitple alleles
B. incomplete dominance
C. codominance
D. dominance
E. pleiotropy

E. pleiotropy

A single gene influences the expression of a number of phenotypes.

Pleio- means greater in quantity

-trope here it means the gene's expression is used in ways not directly obvious to it. The protein product is expressed so it is involved in multiple pathways.