A Researcher Knocks Out a Gene That Is Expressed in the Mouse

A researcher knocks out a gene that is expressed in the mouse embryo during neurulation stages,but this gene is never expressed in the neuroepithelium (neural plate or neural tube) .Hence,she is surprised when the resulting embryos form neural tube defects.What is the explanation for this?

A) All forces for neurulation are generated within the neural plate.
B) All forces for neurulation are generated in non-neural plate tissues.
C) Forces for neurulation are generated in both the neural plate and in surrounding tissues.
D) Neural tube defects are secondary to abnormal body folding, and the gene is likely expressed in the body folds.
E) Neural tube defects are not the result of gene activity, as they occur randomly regardless of where the knocked out gene is expressed.