Rhizopus Stolonifer (Black Bread Mold)is More Likely to Appear on Home-Baked

Rhizopus stolonifer (black bread mold) is more likely to appear on home-baked bread than commercially-distributed bread.A possible explanation is

A) the commercially-distributed bread has been refrigerated while the home-baked bread has not.
B) home-baked bread is more likely to contain chemical preservatives than commercially distributed bread.
C) commercially-distributed bread is more likely to contain chemical preservatives than home-baked bread.
D) home ingredients are more likely to contain fungal spores.
E) home-baked bread will contain more nutrients than commercial breads.