Answer:
B.) Proteins
Step-by-step explanation:
'Carbohydrates' are long chain sugar molecules, can't be that
'Nucleic Acid' is a component in DNA, so that's not it
And 'Lipids' is a fancy way of saying 'fat'.
Through process of elimination it must be 'Proteins', which makes sense because proteins are the "building blocks of the body"
:)