What genotypes can produce the Bombay phenotype?

The Bombay phenotype, also known as Oh phenotype, is a rare blood group that occurs due to a genetic mutation affecting the H gene, which is responsible for producing the H antigen that serves as a precursor for the A and B blood group antigens. Individuals with the Bombay phenotype do not express the H antigen and consequently cannot produce A or B antigens on their red blood cells, even if they carry the genes for these antigens.

The genotype associated with the Bombay phenotype is homozygous for the recessive allele, specifically "hh." This genotype results in the complete absence of the H antigen, leading to the phenotype where A and B antigens are not expressed. Therefore, the correct answer, which indicates that only the hh genotype can produce the Bombay phenotype, accurately reflects the genetic basis of this condition.

Genotypes that include at least one dominant allele (such as HH or Hh) would result in the expression of the H antigen, and those individuals would have either the H antigen alone or the A or B antigens, thus not exhibiting the Bombay phenotype.