Concept:The large intestine contains beneficial bacteria that produce certain nutrients needed by the body.
Explanation:These bacteria synthesize vitamin
K and some
B vitamins through fermentation.
They also synthesize some amino acids, which help maintain the body's amino acid balance.
They do not produce minerals, because minerals are inorganic substances that bacteria cannot make.
They also do not synthesize glucose as a major product in the large intestine.
So the useful substances they synthesize are amino acids and vitamins.
Answer:C. amino acids and vitamins.