Which event would result in an allele or alleles being in a state of perfect linkage disequilibrium?

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Perfect linkage disequilibrium occurs when alleles at two loci are associated more frequently than expected by chance. This can happen when a new mutation arises on a chromosome (A), creating a novel combination of alleles that are initially always inherited together. It can also occur in the case of hybrid offspring from two different species (B), where the combination of alleles from the distinct parental species are initially unique and thus perfectly linked in the hybrid. Crossing over during meiosis (C) actually breaks down linkage disequilibrium by recombining alleles, so it does not result in perfect linkage disequilibrium.

Which Event Would Result in an Allele or Alleles Being