Answer:
Option A, Dominance
Step-by-step explanation:
According to Mendel's principle of dominance , the following can happen
a) Dominance of allele is a form of inheritance of genetic trait in which one allele is recessive to other.
b) The dominant allele can be recessive to any other allele.
c) In a hetero zygote the characteristics associated with a dominant alleles are expressed as phenotype
d) Recessive traits are expressed only in an genotypically homozyous recessive individual
Hence, option A is correct