The answer is A, disaccharides are compose of two simple sugars.
Dissacharide is formed when 2 monosaccharides reacts in the condensation reaction, they produce a Dissacharide and a water molecule during the reaction.
B is not correct because sucrose is a disaccharide. C is also not correct because glucose is a monosaccharide. And last but not least, d is not correct too because monosaccharide is the simplest form of sugar.
Thereofre, the correct answer is a.
