When a normal cell and a cancer cell were fused,the resulting hybrids lost the ability to form tumors in mice.This suggests that

A)The cancer cell alleles are dominant over the normal cell alleles.
B)The cancer cell alleles are recessive to the normal cell alleles.
C)The normal and cancer cell alleles are co-dominant.
D)The original tumor formed as a result of infection by a tumor virus.
E)None of the above.