Sickle cell anemia is known to run in a family. a pedigree chart for this family is shown below
what percentage of the offspring are carriers of the disease but do not have it ?

In pedegree charts, 
a square stands for a male
a circle, female
black filled: phenotype expressed
half filled, heterozygous, hence carriers.

So according to the pedigree diagram, two of the four offsprings (both daughters) are heterozygous, or carriers, of sickle cell anemia.

The answer is 50%  Hopethis helps!

Ithink that b is correct but just in case wait to see if someone else answers