Answer:
C. They are all carbohydrates.
D. They are all used by plants in some way.
Step-by-step explanation:
A. Glucose is a sugar but starch and cellulose and sugars are made from sugars, they are not sugars themselves.
B. They are not proteins. As an easy way to identify them, they have no nitrogen atom in their structure. All proteins do.
C. They are all carbohydrates.
D. They are all used by plants in some way e.g respiration, storing energy and structure