What happens to the 6 carbon atoms of glucose when it is completely degraded?

Degradation means that a large molecule is broken down into simpler ones. In this case, glucose which has a chemical formula of C6H12O6 is broken down into simple parts.

Assuming that the reaction takes the form below, glucose is usually converted into 6 units of carbon dioxide CO2.

C6H12O6  + reactant  -->  6CO2  + product

it's all four options.