Why Are Infants at Risk of Developing Botulism After They

Why are infants at risk of developing botulism after they ingest honey, but adults are not?

A) Bees cultivate C. botulinum bacteria within their hives as a food source. This gets mixed in with the honey they make, and is ingested by infants they are given food containing honey. Adults seldom eat honey, so are not exposed to this organism.
B) The infant digestive tract is immature and is extremely susceptible to the effects of botulism toxin which found in the honey in relatively high levels. The adult digestive tract is immune to the effects of botulinum toxin because of M cells and Peyer's patches.  
C) The spores of C. botulinum produce a strong endotoxin. This endotoxin has little effect on adults because their immune system is fully developed. Infants, however, do not have a fully developed immune system and therefore far more susceptible to the toxin than adults.
D) Honey can contain C. botulinum endospores. These may germinate in the intestines of infants that have eaten it, leading to colonization and pathogenesis as the bacteria begin forming botulism toxin. Adults' normal intestinal microbiota will out-compete the new microbes.
E) Honey can contain C. botulinum endospores. These may germinate in the intestines of adults that have eaten it. The bacteria are then sampled by M cells within the adult intestinal tract, leading to the development of botulism. Infants do not have any M cells in their tract.