Answer: a) a different paternal and maternal allele at a particular locus
Explanation: Hetero-zygote are referred as the organisms that represent the two different alleles of a particular gene. It can have different individual paternal and maternal allele from a gene.They have the nature of establishing alleles that among the two alleles, one of them has a dominant approach. Therefore the correct option for the given statement in the question is option(a) .