You Insert a Gene for Tetracycline Resistance into One Plasmid

You insert a gene for tetracycline resistance into one plasmid and a gene for ampicillin resistance into another plasmid.You successfully introduce both plasmids into a sample of E.coli cells,but fail to grow any of them in culture medium with both antibiotics present in it.What could best explain the problem?

A) Random mutation has inactivated the antibiotic resistance genes
B) Plasmid incompatibility will not allow both plasmids to persist
C) E) coli cannot maintain two plasmids
D) The plasmid(s) have integrated into the bacterial chromosome
E) A phage has neutralized one of the plasmids