Alarge glycogen molecule is converted into may smaller glucose molecules. what type of chemical reaction is this

Answer is: catabolism.

Missing question:
Synthesis.
Catabolism.
Rearrangement.
Anabolism.
Catabolism (the set of metabolic pathways) breaks down large molecules (in this example glycogen, a polysaccharide) into smaller units (in this example glucose, a monosaccharide).
Glycogen is the main storage form of glucose in the body.