Sickle- cell anaemia is an autosome linked recessive trait that can be transmitted from parents to the offspring when both the partners are carrier for all the gene (or heterozygous ).The disease is controlled by a single pair of allele,`Hb^(A)` & `Hb^(S)`. Out of the three possible genotypes only homozygous individuals for HbS `(Hb^(s) Hb^(s))` are lethal. Select the right option in which X,Y and Z are correctly identified