The given diagrammatic representation shows one of the categories of small molecular weight organic compounds in the living tissues. Identify the category shown and the one blank component "X" in it `:`
A. `{:("Category",,,,"Component"),("Amino acid",,,,NH_(2)):}`
B. `{:("Category",,,,"Component"),("Nucleotide",,,,"Uracil"):}`
C. `{:("Category",,,,"Component"),("Nucleoside",,,,"Adenine"):}`
D. `{:("Category",,,,"Component"),("Cholesterol",,,,"Guanine"):}`
