Question

Carlos is studying thalassemia, a genetic blood disorder that occurs among people of Mediterranean descent. The disorder causes the body to make abnormal hemoglobin, the oxygen carrier in the blood. Carlos wants to use the pedigree below to learn about the patterns of inheritance of thalassemia.

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Which statement describes the pattern of inheritance for thalassemia?
The allele for thalassemia is dominant and is found on an autosome.
The allele for thalassemia is recessive and is found on an autosome.
The allele for thalassemia is found on a Y sex chromosome.
The allele for thalassemia is found on an X sex chromosome.