Sickle-cell anaemia is an inherited disorder caused by the allele $\mathrm{Hb}^S$. $\mathrm{Hb}^A$ is the normal allele. A woman has no symptoms of the disease, but her brother does have symptoms. If her mother and father both have no symptoms, which statement is correct?
- AThe woman has the genotype $\mathrm{Hb}^S\mathrm{Hb}^S$.
- BThe woman’s brother has the genotype $\mathrm{Hb}^A\mathrm{Hb}^A$.
- CThe woman’s father and mother both have the genotype $\mathrm{Hb}^A\mathrm{Hb}^S$.
- DThe woman’s father and mother both have the genotype $\mathrm{Hb}^S\mathrm{Hb}^S$.