Darnell and Tinaka Are Each Carriers of an Autosomal Recessive

Multiple Choice

Darnell and Tinaka are each carriers of an autosomal recessive disorder that is lethal in early childhood.They want to have a child who is free of the disease,so they have preimplantation genetic diagnosis.Unfortunately,their child has the disease.A scientific explanation is that

A) the blastomere that was tested had undergone a somatic mutation, making it not representative of the rest of the embryo.
B) Darnell was not really the father.
C) the 7 cells of the remaining embryo each underwent a mutation, so the sampled cell was not representative.
D) Darnell or Tinaka is really homozygous recessive, and not heterozygous.
E) a technician mixed up the embryos.