Answer:
One heterozygous parent, and one homozygous recessive parent
Explanation:
Lets say we have allele B that is the dominant allele, and b is the recessive allele. A parent with the genotype Bb will show the dominant phenotype, and a parent with the genotype bb will show the recessive phenotype.
The alleles they can pass on to the next generation will be B and b for the parent with the dominant phenotype, and only b for the parent with the recessive phenotype.
See the attached image for punnet square.
The punnet square shows half dominant (Bb) and half recessive (bb) offspring
