Question

Which of the following molecules link together to form starch?

Answer 1

It is Glucose because it has special molecules that make link with the others.

Answer 2

Glucose which can also be fats from excess carbohydrates. 
Carbohydrates actually get stored in the form of long polymers of glucose molecules or as glycogen starch. They provide energy to the animals for performing their daily duties. Carbohydrates are generally considered the fuel for all organisms, and without this most animals would become sloth and would be unable to perform the regular jobs. Carbohydrates are actually very easy to metabolise and hence generate quick energy.