Even though you are missing the 4 choices, I would guess the answer is PROTEINS. They have 4 levels of sctructure: Level 1) The amino acid sequence.Level 2) The shape that these sequences take caused by hydrogen bonds (ex. Alpha helix, Beta Sheet) Level 3) The ''fold'' or ''position'' that the shaped sequence from level 2 take, caused by other molecular attractions. Level 4) The combination of multiple ''level 3'' protids to make a more complex protein.