Answer:
e. all of the above mechanisms for establishment of the microbiota in newborns
Explanation:
To a greater or lesser extent, all of the above contribute to the development of a newborn's microbiota.
The concept here is that the baby is immersed in a novel environment. It implies that any minimal interaction or physical contact can lead to the conditioning of the microbiota depending on that environment.
Also to clarify, there is not only one microbiote. There is a digestive, an intestinal, pulmonary, etc...
