16. Genetically knocking out both copies of the p53 gene in rats ______.(A) does not have any effect unless the rats live outside of the laboratory and are exposed to various types of stress. (B) increases cell death by apoptosis, leading to developmental defects. (C) results in a lower malignancy rate, but the rats are otherwise seemingly normal. (D) results in a higher rate of cancer onset, but the rats are otherwise seemingly normal. (E) is embryonic lethal.