s would be secondary Explanation:
just cause
Lipids are unique because, they are made from one carbon skeleton unlike the other macro molecules groups which are made from smaller building blocks.
With the exception of steroid hormones, lipids are generally hydrophobic. Also lipids are relative small molecules when compare in size with other macromolecules.
It's biproducts or by cutting it open and find out.
The most appropriate answer is D !
in respiration oxygen and glucose( food substance) combines to form energy and CO2 !
