Final answer:
Proteins function in cells primarily for cell communication and oxygen transport through molecules such as hemoglobin, as well as acting as enzymes, structural components, and antibodies.
Therefore, option B is correct.
Step-by-step explanation:
The function of proteins in cells that corresponds to the choices provided is cell communication and oxygen transport. Proteins serve multiple vital roles, including acting as enzymes that catalyze chemical reactions, providing structural support, functioning as receptors that facilitate cell signaling, and as transport proteins that move molecules throughout the body, such as hemoglobin which binds oxygen and transports it through the bloodstream. Additionally, proteins can also be seen as connective and motor proteins in muscle tissues and as antibodies that target foreign substances for destruction.