The difference between incomplete dominance and codominance is that: A. in incomplete dominance, the offspring exhibit the traits of both parents, whereas in codominance, the offspring do not exhibit the traits of either parent. B. incomplete dominance results from a multi-allelic system, whereas codominance results from a two-allelic system. C. in incomplete dominance, the trait under observation is produced by the a single allele, whereas in codominance, the trait is produced by a combination of multiple alleles. D. in incomplete dominance, the trait under observation is produced by the combination of multiple alleles, whereas in codominance, the trait is produced by a single allele.