When a cell is stressed because something is wrong, these L flags become very active. O Protein
O carbohydrate
lipid
cholesterol

The correct option is;

Protein

Explanation:

Stress proteins are the class of proteins used to mediate cellular stress response. There are two types of stress proteins including the stress activated proteins and the dual functioning, stress response and cell function protein. By being a primary source of survival of cells under stress has resulted in the conservation and associated existence of the similar stress proteins in different classes of living organisms.

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.

the supermassive black hole is in the middle of the galaxy.