Extraneous means "irrelevant or unrelated to the subject being dealt with."
Hybrid means "a thing made by combining different elements."
Concomitant means "naturally accompanying or associated with."
Extraneous is the word that fits. Concomitant is actually the opposite of this.
Answer:
organ
Explanation:
A sprain is an injury where as belly is where the stomach is, and digestion is what the stomach does.
