B would be the most likely answer.
Answer:
The phylum Hemichordata is the one that could form an evolutionary connection between the chordates and non-chordates.
Explanation:
To the phylum Hemichordata belongs a genus that scientists believe could explain how the chordates could evolve from the non-chordates. This genus is Balanoglossus, of the class Enteropneusta.
Balanoglossus is similar to a worm, whose habitat is the seabed, and like other hemicordates it has a stomach, a structure that forms part of its digestive system and fulfills the functions of a spine.
Learn more:
Chordates and non-chordates brainly.com/question/1387264
(Oxygenated non-saline) is in the missing spot
The answer to your question is Oxygen
