The right answer is 3 water molecules.
A condensation reaction is a chemical reaction in which two molecules, or two parts of the same molecule, combine to form a molecule (the condensate) by eliminating a single molecule (the by-product), such as water. (most often), hydrogen sulphide, methanol or acetic acid.
Here are the reactions for this question:
Glucose + Glucose → G-G + by-product (water).
G-G + Glucose → G-G-G + by-product (water).
G-G-G + Glucose → four-glucose-polymer + by-product (water).
