Final answer:
The stomodeum and primitive pharynx are separated by the A) Oropharyngeal membrane, which is a temporary embryological structure that eventually disintegrates.
Step-by-step explanation:
The stomodeum and primitive pharynx are separated by the A) Oropharyngeal membrane. The stomodeum is an embryonic precursor to the mouth, and the primitive pharynx is an early developmental form of the pharynx. The oropharyngeal membrane is a temporary structure that disintegrates to connect the stomodeum to the primitive gut, allowing for the formation of the digestive and respiratory tracts.