Final answer:
The three monosaccharides are glucose, fructose, and galactose, all of which are isomeric hexoses with the chemical formula C6H12O6 but have different structures. The answer is option D.
Step-by-step explanation:
The student asked which of the following sets are all monosaccharides: A) fructose, galactose, lactose; B) maltose, sucrose, lactose; C) glucose, fructose, sucrose; D) glucose, fructose, galactose. The correct answer is: glucose, fructose, and galactose. These are all common monosaccharides and are isomeric hexoses, meaning they have the same chemical formula, C6H12O6, but differ structurally. Galactose is part of lactose, and fructose is found in both sucrose and fruit. Morse specifically, glucose and galactose are aldoses, while fructose is a ketose.