Multiple alleles Questions in English

(D) person with blood group '$O$' has the genotype '$ii$'. This means the person must inherit one '$i$' allele from the father and one '$i$' allele from the mother.
$(A)$ Father: $I^Ai$, Mother: $I^Bi$: Possible offspring genotypes include $I^AI^B, I^Ai, I^Bi, ii$. Thus, blood group '$O$' $(ii)$ is possible.
$(B)$ Father: $I^Ai$, Mother: $I^Ai$: Possible offspring genotypes include $I^AI^A, I^Ai, ii$. Thus, blood group '$O$' $(ii)$ is possible.
$(C)$ Father: $I^Bi$, Mother: $I^Bi$: Possible offspring genotypes include $I^BI^B, I^Bi, ii$. Thus, blood group '$O$' $(ii)$ is possible.
$(D)$ Father: $I^AI^B$, Mother: $I^Ai$: Possible offspring genotypes include $I^AI^A, I^AI^i, I^AI^B, I^Bi$. The possible blood groups are $A$ and $AB$. Blood group '$O$' $(ii)$ is not possible because the father does not carry the '$i$' allele.

(B) Step $1$: Perform the cross between the parents with genotypes $I^A I^B$ and $I^A I^O$.
Step $2$: The possible combinations are:
- $I^A I^A$ (Phenotype: Blood group $A$)
- $I^A I^O$ (Phenotype: Blood group $A$)
- $I^A I^B$ (Phenotype: Blood group $AB$)
- $I^B I^O$ (Phenotype: Blood group $B$)
Step $3$: Count the distinct genotypes: $I^A I^A$, $I^A I^O$, $I^A I^B$, and $I^B I^O$ (Total $4$ genotypes).
Step $4$: Count the distinct phenotypes: Blood group $A$, Blood group $AB$, and Blood group $B$ (Total $3$ phenotypes).
Conclusion: There are $4$ genotypes and $3$ phenotypes possible.