Escherichia coli O157:H7 was first observed in fast-food hamburger meat. More recently, it has been associated with contamination of spinach and other vegetables. How did the spread of this strain from meat to vegetables happen?

A) It picked up genes for plant virulence.
B) Strain O157:H7 can grow as a plant endophyte.
C) It has become a psychrotroph and can grow in refrigerated foods.
D) It produces toxins that can survive on plant material.
E) This bacterial strain has lost genes needed to grow in meat.