Why Are "Fortified" Foods More Likely to Spoil Than Are

Why are "fortified" foods more likely to spoil than are unfortified foods?

A) The addition of vitamins or minerals makes the food more nutritious for microbes as well as humans.
B) Vitamins are added to "fortified" foods by adding the microbes that produce the vitamins to the food item.
C) Every step of modification or manipulation of food increases the chance for contamination.
D) The addition of nutrients creates an osmotic environment suitable for a wide range of microbes.
E) The vitamins require a neutral pH environment, which is suitable for many microbes.