Which Mendelian idea is depicted by a cross in which the F1 generation resembles both the parents?

In co-dominance, the resulting progeny inherits the characters of both the parents because neither of the alleles is recessive and both the alleles express their phenotype in the heterozygous condition. Eg: A cross between red flowers and white flowers of Camellia will result in flowers which have both red and white flecks. Law of dominance holds true when the other allele is recessive and the heterozygous F1 generation resembles only dominant parent. So the correct solution is option D.